Acalephs is no longer an exception to the simultaneous appearance of all the types of Radiata in the lowest fossiliferous formations, and the peculiar characters which these old Hydroid corals present appears in a new and very instructive aspect." A. Agassiz includes the Tabulata amongst the Hydrozoa. He notices "that the absence of radiating partitions in the Tabulata seems to show without much doubt that their true place is among the Hydroids." It is true that Prof. Agassiz has not observed the Medusa-buds on the specimens he has figured, yet the Hydroid character of the animal and their similarity to Halocharis-like Hydroids is very striking (Havard Catalogue, 1865, p. 219). Prof. Alexander Agassiz informs me that his father still holds these opinions, and that new researches have satisfied him about the correctness of the drawings which have been lately reproduced. "Millepora is not an actinoid polyp, but a genuine Hydroid, closely allied to Hydractinia." This very strong expression of opinion is founded upon the appearance presented by the polyps of Millepora alcicornis, the drawing of which has been reproduced by A. Agassiz. Now the distinction between the Actinozoa and the Hydrozoa is well marked; in the first the generative apparatus is included in the gastric and perigastric cavities, and in the last the digestive and generative organs are perfectly apart. Every variety of tentacular and disk apparatus may exist in either, but the external development of the gemmules, ova, and embryonic forms must be recognized before any Cœlenterate animal can be associated with the Hydrozoa. Here is the point at which Agassiz fails. His researches are only suggestive, until the generative organs are recognized on the protruded polypes of Millepora, and until the mesenterico-ovarian layers are proved not to exist within the calices. The external resemblance of the Millepore polypes to the sterile Hydractinia is evident. The remarks upon Favositidæ, Sideroporæ, and other genera, made by Agassiz in consequence of the assumption that Millepora is Hydrozoan, are of doubtful value; and I must refer back to my analysis of the Tabulata to show how a confused classification between both classes imperils research. Sideropora is not a tabulate form even. A careful examination of Columnaria satisfies me that Agassiz's description of the lamellæ fails in that genus; and inasmuch as the wavy lines of Gorgonia and Corallium are connected with the water system of the species, they can have no possible relation with the radiate amellæ or groovings of the Milleporan calices. The homologues of the grooves are the depressions and irregular interstriated portions on top of the cœnenchyma between the calices in the Tabulata. The perforate walls and the septa of the true Favositida seem to remove them from the range of the remarks of Agassiz, which may well deserve attention, so far as Millepora is concerned, for it is a genus with marked distinctions from all other corals. It is not reasonable to include the Rugosa, because some of them have no tabulæ, and others have them so much like dissepiments, or associated with dissepiments, that we are impressed with the unimportance of the differentiations established by the presence of horizontal tabulæ. It is most important that the minute structure of the Milleporida should be thoroughly investigated, and any report on the Paleozoic corals must be very incomplete without a detailed description of its study. With coenenchyma .... Section TABULATA. Families. J Milleporida. Coenenchyma cellular. Without cœnenchyma.. Halysitida. Walls imperforate. MILLEPORIDE ACROPORIDE FAVOSITIDE HALYSITIDE ALVEOLITIDE Incerta sedis Chatetes. Lyellia. Thecostegites, Axopora. Acropora, Seriatopora, Pocillopora, Dendropora, Rhab- Favosites, Koninckia, Favositipora, genus nov. (Kent). Syringopora. JAlveolites. ALCYONARIA. Monticulipora. Dania. Stellipora. Labechia. IV. The Rugosa.-MM. Milne-Edwards and Jules Haime observe (op. cit. vol. iii. p. 323), "that this division comprehends simple and compound corals, and that the septal apparatus never forms six distinct systems, and appears to be derived from four primitive elements. Sometimes this disposition is shown by the great development of four principal septa, or by the existence of four depressions which occupy the bottom of the calice and take on a cross-like look. In other instances there is observed only one of these depressions or excavations, or one large septum interferes with the regularly radiate and star-shape of the septal arrangement. Finally, thero are instances where no traces of distinct groups or systems of septa can be recognized, and where the septa are represented by numerous striæ arising on the upper surface of the tabulæ or dissepiments near the calicular margin." They continue as follows:-"The corallites are always perfectly distinct amongst themselves, and are never united by independent conenchyma. The walls are in general very slightly developed. The visceral chamber is * Millepora is a most aberrant genus if it is one of the Madreporaria Tabulata. I have not yet satisfied myself about the Hydroidean characteristics of its soft parts; but an examination of the coenenchyma of a series of species throws great doubt upon the Madreporarian affinities. The relation of Heliopora to Heliolites is of the closest. ordinarily occupied by a series of tabule or vesicular endotheca, and the endotheca often occupies the greater part of the corallum. The septal lamina, although generally very incomplete, are never perforated or 'poutrellaire;' finally, their lateral faces are not furnished with synapticulæ, and are only rarely granular. "The individual corallites increase by gemmation, and never by fissiparity. The buds are generally calicular, and this form of gemmation may continue in the same individual. In some cases the gemmation is lateral.” The originators of the "Rugosa" divide them into four families : 1. Stauridæ. 2. Cyathoxonida. 3. Cyathophyllida. In criticising this classification some definite plan must be adopted, which should refer to the philosophy of the classification of the Aporosa and Perforata. In fact the scheme of generic subdivision and differentiation adopted in the Neozoic corals can be made to apply to those of the Palæozoic age. Thus an essential distinction is made amongst the Neozoic corals by the simple or compound nature of the corallum. Simple Caryophyllinæ constitute a series of genera, and the compound forms are separated as Conocyathi. Now in the Paleozoic genus Cyathophyllum, MM. Milne-Edwards and Jules Haime admit, in direct opposition to the Neozoic scheme, both simple and compound forms. This, I think, is an error, but only an error of classification, for there can be no reasonable doubt of the intimate genealogical relation of the simple and compound genera of Cyathophyllum. Families*. 1. STAURIDE.-Genera: Stauria, Holocystis, Polycælia, Metriophyllum, Conosmilia. Of these Holocystis is a Lower Greensand form, and Conosmilia is Australian and Tertiary. MM. Milne-Edwards and Jules Haime place the Stauridæ first in their list of families; but it would have made the classification more simple if the second family took their place; and I propose to change the order of arrangement, but proceed at present in the recognized method. There is a well-developed wall in the Stauridae; the septa are continuous from the top to the bottom of the calice, and are eminently quaternary in their arrangement. The endotheca assumes the vesicular structure between the septa, and then crosses over in the form of horizontal tabulæ. The Stauridae approach the Cyathophyllidæ more than the Cyathoxonida; and, indeed, the only essential distinction between the first two families is in the truly lamellar state of the septa in the first instance, and in the incomplete condition of them in the second. Nevertheless it should constitute a family distinction. Two of the Stauridian genera are compound, and three are simple forms. Stauria, which as yet has not been found in British strata, has neither columella nor costæ, whilst Holocystis has both of these structures. There is no reason why the last-named genus should not be the lineal descendant of the former. Both were probably shallow-water forms in the neighbourhood of reefs. The simple forms Conosmilia and Polycalia are closely allied, and the presence of the first in the Australian Tertiaries, and of the other in the Euro See Hist. Nat. des Coralliaires, vol. iii. p. 325 et seq. (Milne-Edwards and Jules Haime). pean Permian, is highly suggestive. The remaining form, Metriophyllum, offers a great difficulty, for if the received classification be adopted, the genus is very aberrant. Thus Metriophyllum has not four principal septa, but the septa are arranged in four groups, a gap or kind of septal fossula being between each group. The British Devonian species (M. Battersbyi, Ed. & H.) was founded upon a transverse section of a slab, and therefore the entire nature of the septa could hardly be determined. The question arises at once, what do those septal fossulæ mean? And another follows very naturally, are they in relation with the primary septa? I think that they denote a difference in the physiology of the polype, for they would permit of a deeper development of the visceral cavity and an enlarged condition of the ovarian apparatus. Moreover, these fossulæ may have much to do with the growth of the coral in calibre and in septal number; and, furthermore, Lindström's admirably suggestive paper on the operculated structures, necessitates much attention being paid to them. Can there be any genealogical classification which will connect in one family such different forms as Metriophyllum and Polycœlia? I think not. Eliminating, then, Metriophyllum from the Stauridae, I propose to permit the genus to remain per se for the present. 2. CYATHOXONIDE.-Genera: Cyathoxonia, Paleozoic; Haplophyllia (Pourtales) and Guynia (Duncan), recent. This group has no endotheca, and resembles the Turbinolidæ amongst the Neozoic corals, but it has the quaternary arrangement of the septa. All the forms are simple. Cyathoxonia preceded the others, and all are closely allied. The foreshadowing of the Neozoic forms in the Paleozoic Cyathoxonidæ is evident enough. Report on the Heat generated in the Blood during the process of Arterialization. By ARTHUR GAMGEE, M.D., F.R.S.E., Lecturer on Physiology in the Extra-Academical Medical School of Edinburgh. IN a Report which was submitted to the British Association in Liverpool last year*, I very shortly alluded to the objects which I had in view in commencing an investigation on the very obscure subject of the heat generated during the arterialization of blood. I pointed out that two methods of research suggested themselves as likely to elicit facts which would lead to a solution of the problem, and I stated that both these methods had been employed by previous observers. The first method, which would at first sight appear likely to furnish us with most important data, consists in ascertaining the temperature of the blood in the right and left ventricles of the heart of living animals. If our methods of experimenting were free from the great fallacies which are introduced when we are compelled to interfere, in a serious manner, with the central organ of the circulation, and if it resulted that the left side of the heart contained blood warmer than that of the right side, we should be driven to the conclusion either that during the process of absorption and combination of the oxygen of the air a very perceptible evolution of heat had oc * Report of the Liverpool Meeting, p. 228. curred, or that within the pulmonary vessels considerable oxidation processes of the blood contained in them had taken place. If, on the other hand, the temperature of the left side were the same as that of the right side, or lower, the question would still remain an open one; for heat might be evolved in the lungs, and yet the quantity might be insufficient to counterbalance the loss of heat due to the evolution of large quantities of watery vapour, of carbonic acid, and to the heating of the air which we daily inspire. The first method, or that which consists in ascertaining the temperature of the two sides of the heart, need scarcely be touched upon at present; and I shall merely confine myself to the statement that, in the hands of the most experienced and reliable physiologists, and specially in those of Professor Claude Bernard, it has led to the curious result that the blood which reaches the left ventricle is colder than that which leaves the right. This result would, at first sight, appear to prove that if any heat be evolved in the lungs, its amount is not sufficient to compensate the losses to which I have already alluded, and rendered it absolutely essential that fresh experiments should be conducted by a second method, which consists in ascertaining whether, when venous blood removed from the body is agitated with oxygen or atmospheric air, any changes occur in its temperature. The first step in the inquiry consisted in ascertaining the specific heat of blood, for none of the experiments previously made had led to trustworthy results. Dr. Crawford had, in the last century, advanced a theory of animal heat which was based upon an assumed difference in the specific heat of arterial and venous blood: he supposed that the former possessed a very high, and the latter a comparatively low specific heat; so that in becoming arterialized in the lungs, the heat resulting from the condensation, solution, and probable chemical combination of oxygen with the blood became latent, being, however, evolved as the blood circulated through the body, when, becoming venous, it acquired a continually diminishing specific heat. Dr. John Davy, in his Researches, Physiological and Anatomical,' vol. i. p. 141, in a chapter entitled "On the Capacities of Venous and Arterial Blood for Heat," described experiments which contradicted the hypothesis of Crawford as to the difference in the specific heat of the two varieties of blood, although the extraordinary discrepancies between different experiments rendered it impossible that any calculations could be based upon Dr. Davy's results. In his experiments, Dr. Davy made use of defibrinated blood, employing for the determination of specific heat the methods of mixture and rate of cooling. In the experiments which I performed last year, and which are published in the last volume of the Reports of the British Association, I made use of the method of mixture, taking care to adopt all the precautions which modern experience has suggested. Making use of the perfectly fresh blood of the ox, which was sometimes venous, sometimes arterial, I obtained remarkably concordant results, the mean of which gave 1·02 as the coefficient of the specific heat of blood. Having made this determination, I could pass to the experiments intended to determine whether, in being arterialized, blood which is perfectly venous becomes hotter. As a preface to my own researches on this subject, it is incumbent upon me to allude to all the observations which have been made on this subject. In the second volume of Dr. Davy's Researches, Physiological and Anatomical,' at p. 168 a section is devoted to the following question:-"When oxygen is absorbed by the blood, is there any production of heat?" "To endeavour to determine this point," says Dr. Davy, " of so much interest in connexion with the theory of animal heat, a very thin vial, of the |