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one would be led to presuppose the Trilobites possessed of organs of locomotion of a stronger texture than mere branchial frills.
The objection raised by Drs. Dana and Verrill to the special case of appendages in the Asaphus assumed by Mr. Billings to possess ambulatory legs, is that the said appendages were merely the semicalcified arches in the integument of the sternum to which the true appendages were attached.
A comparison, which these gentlemen have themselves suggested, between the abdomen of a Macruran Decapod and the Trilobite in question is the best refutation of their own argument.
The sternal arches in question are firmly united to each tergal piece at the margin, not along the median ventral line. If, then, the supposed legs of the Trilobite correspond to these semicalcified arches in the Macruran Decapod, they might be expected to lie irregularly along the median line, but to unite with the tergal pieces at the lateral border of each somite. In the fossil we find just the contrary is the case ; for the organs in question occupy a definite position on either side of a median line along the ventral surface, but diverge widely from their corresponding tergal pieces at each lateral border, being directed forward and outwards in a very similar position to that in which we should expect legs (not sternal arches) to lie beneath the body-rings of a fossil crustacean. The presence, however, of semicalcified sternal arches presupposes the possession of stronger organs than mere foliaceous gill-feet; whilst the broad shield-shaped caudal plate suggests most strongly the position of the branchiæ. In the case of the Trenton Asaphus I shall be satisfied if it appears, from the arguments I have put forward, that they are most probably legs—feeling assured that more evidence ought to be demanded before deciding on the systematic position of so large a group as the Trilobita from only two specimens*.
With regard to the embryology and development of the modern KingCrab (Limulus polyphæmus), we must await the conclusions of Dr. Anton Dohrn before deciding as to the affinities presented by its larval stages to certain of the Trilobita, such relations being only in general external form. Dr. Packard (Reports of the American Association for the Advancement of Science, August 1870) remarks, “ The whole embryo bears a very near resemblance to certain genera of Trilobites, as Trinucleus, Asaphus, and others;" and he adds, “ Previous to hatching it strikingly resembles Trinucleus and other Trilobites, suggesting that the two groups, should, on embryonic and structural grounds, be included in the same order, especially now that Mr. E. Billings has demonstrated that Asaphus possessed eight pairs of 5-jointed legs of uniform size."
Such statements are apt to mislead unless we carefully compare the characters of each group. And first let me express a caution against the too hasty construction of a classification based upon larval characters alone.
Larval characters are useful guide-posts in defining great groups, and also in indicating affinities between great groups; but the more we become acquainted with larval forms the greater will be our tendency (if we attempt to base our classification on their study) to merge groups together which we had before held as distinct.
have, as a matter of course, been considered as belonging to a much lower group than the Isopoda, in which the normal number of somites is seven. Whilst admitting the justice of this conclusion, we do not think it affords any good ground for rejecting the proposition that the Isopoda may be the direct lineal descendants of the Trilobita.
* One in Canada and one in the British Museum, both of the same species.
To take a familiar instance: if we compare the larval stages of the Common Shore-Crab (Carcinus moenas) with Pterygotus, we should be obliged (according to the arguments of Dr. Packard) to place them near to or in the same group
The eyes in both are sessile, the functions of locomotion, prehension, and mastication are all performed by one set of appendages, which are attached to the mouth; the abdominal segments are natatory, but destitute of any appendages.
Such characters, however, are common to the larvæ of many crustaceans widely separated when adult, the fact being that in the larval stage we find in this group what has been so often observed by naturalists in other groups of the animal kingdom, namely, a shadowing forth in the larval stages of the road along which its ancestors travelled ere they arrived from the remote past at the living present.
If we place the characters of Limulus and Pterygotus side by side, and also those of Trilobita and Isopoda, we shall find they may be, in the present state of our knowledge, so retained in classification.
Limulus (Fossil, and living). 1. Eyes sessile, compound.
1. Eyes sessile, compound. 2. Ocelli distinctly seen.
2. Two ocelli distinctly seen. 3. All the limbs serving as mouth- 3. All the limbs serving as mouthorgans.
organs. 4. Anterior thoracic segments bear- 4. All the thoracic segments bear
ing branchiæ or reproductive ing branchiæ or reproductive organs.
organs. 5. Other segments destitute of any 5. Other segments destitute of any appendages.
appendages. 6. Thoracic segments unanchylosed. 6. Thoracic segments anchylosed. 7. Abdominal segments free and well 7. Abdominal segments anchylosed developed.
and rudimentary. 8. Metastoma large.
8. Metastoma rudimentary.
Isopoda (Fossil, and living). 1. Eyes sessile, compound.
1. Eyes sessile, compound. 2. No ocelli visible.
2. No ocelli visible. 3. Appendages partly oral, partly 3. Appendages partly oral, partly
ambulatory, arranged in pairs. ambulatory, arranged in pairs. 4. Thoracic segments variable in 4. Thoracic segments usually seven,
number, from 8 even to 28, free free and movable (animal and movable (animal scmetimes sometimes rolling into a ball).
rolling into a ball). 5. Abdominal series coalesced to 5. Abdominal somites coalesced, and
form a broad caudal shield, forming a broad caudal shield,
bearing the branchiæ beneath. bearing the branchiæ beneath. 6. Lip-plate well developed.
6. Lip-plate small. Should our further researches confirm Mr. Billings's discovery fully, we may propose for the second pair of these groups a common designation, meantime we give the above as representing the present state of our knowledge.
Report of the Committee appointed at the Meeting of the British
Association at Liverpool, 1870, consisting of Prof. JEVONS, R. DUDLEY BAXTER, J. T. DANSON, JAMES HEYWOOD, F.R.S., Dr. W. B. HODGSON, and Prof. WALEY, with EDMUND Macrory as their Secretary, "for the purpose of urging upon Her Majesty's Government the expediency of arranging and tabulating the results of the approaching Census in the three several parts of the United Kingdom in such a manner as to admit of ready and effective
comparison." Your Committee after their appointment held meetings in London, and agreed upon the following Memorial :
“ UNIFORMITY of Plan for the Census of the UNITED KINGDOM. “ To the Right Honourable Henry Austin Bruce, M.P., &c. &c., Her Ma
jesty's Principal Secretary of State for the Home Department. “Memorial of the Committee of the British Association, appointed in Liver
pool, September 1870, for the purpose of urging upon Her Majesty's Government the expediency of arranging and tabulating the results of the approaching Census in the three several parts of the United Kingdom in such a manner as to admit of ready and effectual comparison.
“Your memorialists beg respectfully to represent that the value of statistical information depends mainly upon the accuracy and expedition with which comparisons can be made between facts relating to different districts.
“They also consider that the ease and rapidity with which researches in the census tables can be made is one principal object to be held in view in determining the form of their publication. They therefore desire that not only should the enumeration of the people be conducted in all places in an exactly uniform manner, so far as is compatible with the terms of the several Census Acts, but that there should be no divergence in the modes of tabulating and printing the results. They wish that the tables for England, Scotland, and Ireland should form as nearly as possible one uniform and consistent hole.
“Your memorialists could specify a great many points in which there was divergence between the tables for 1861, but they will mention only a few of the more important cases.
"1. The detailed population tables of England, Scotland, and Ireland differ as regards the periods of age specified. The Scotch report gives twenty-one intervals of age, the Irish report generally twenty-two, and the English only thirteen. Either one-third of the printed matter in the Scotch and Irish tables is superfluous, or that in the English tables deficient.
“2. The classification of occupations is apparently identical in the three reports, but there is much real discrepancy between the Irish and English reports, rendering exact comparison difficult.
"3. In the Irish report there is no comparison and classification of occupations according to age, classification according to religions being substituted, although such a classification could not be made in England or Scotland.
“4. In the appendix to the English report appears a table (No. 56), giving most important information as regards the numbers of the population at each year of age. Inconvenience has been felt from the want of similar information concerning the populations of Scotland and Ireland.
“5. In the appendix to the Irish report they find some interesting Tables (II., III., and IV.), to which there is nothing exactly corresponding in the other reports, so far as they have been able to discover.
“6. The tables, even when containing the same information, are often stated in different forms and arrangements, seriously increasing the labour of research.
“ Your memorialists therefore beg to suggest :“I. That the principal body of tables relating to the numbers, age, sex,
birthplace, civil condition, and occupation of the people should be drawn up and printed in an exactly identical form for the three
parts of the United Kingdom. “II. That while the Commissioners may with great advantage continue
to exercise their free discretion in drawing up such minor tables as appear to have special interest for distinct localities, they should agree to prepare in a uniform manner such minor or summary tables as may be of importance as regards all the parts of the
United Kingdom. “ III. That a general Index of Subjects should be prepared for the whole
of the reports, appendices, and tables, so that an inquirer can readily ascertain where the corresponding information for different parts of the United Kingdom is to be found, without making, as hitherto, three independent searches through a mass of complex and
almost unindexed information. "It would appear that the officers engaged in superintending the Census of 1861 acted to a certain extent in concert and agreement.
“Your memorialists beg respectfully to request that those officers be instructed, on the present occasion, to confer with each other prior to drawing up the tables for 1871, with a view of preserving perfect uniformity in their operations, and avoiding all such divergencies in the three reports as are not required by the Census Acts or the essential differences of the three Kingdoms.
"Signed on behalf of the Committee, 8th December, 1870.
“ W. STANLEY JEVONS, F.S.S.,
the Advancement of Science, Liverpool, 1870.
Vice-President of the Statistical Society. “ Jacob WALEY, F.S.S.,
One of the Secretaries of the Statistical Society. “Edmd. MACRORY, M.A., Secretary of the Committee of the British Association for a Uni
formity of Plan in the Census Tables of the United Kingdom.”
The above memorial was immediately presented to the Right Hon. H. A. Bruce, M.P., Her Majesty's Principal Secretary of State for the Home Department, and has been by him referred to the Registrars General for their report thereon.
The returns of the Census having only recently been collected, too little time has as yet elapsed for the perfect arrangements of the tables to be completed, but your Committee have reason to believe that the recommendations contained in the above memorial will ultimately be, to a considerable extent, adopted by Her Majesty's Government.
Postscript.—Since the above Report was drawn up, the Committee have received a formal reply from the Home Office (dated 26th September, 1871), informing them that the Home Secretary “ has desired the Registrar General for Scotland, and has requested the Lord Lieutenant to desire the Census Commissioners in Ireland, to frame their tables in conformity with those submitted by the Registrar General for England and Wales, and approved by Mr. Bruce, as far as circumstances will admit; and that with this view he has instructed the above-mentioned officers to place themselves in communication with the Registrar General for England and Wales."
Report of the Committee appointed for the purpose of Superintending
the Publication of Abstracts of Chemical Papers. The Committee consists of Prof. A. W. WILLIAMSON, F.R.S., Prof. H. E. Roscoe,
F.R.S., Prof. E. FRANKLAND, F.R.S. The Committee are glad to be able to announce that regular monthly reports of the progress of Chemistry have been published since April 1st, 1871, by the Chemical Society. These Reports have been rendered, as far as possible, complete by abstracts, more or less full, of all papers of scientific interest, and of the more important papers relating to applied chemistry. The abstracts have been made by chemists, most of whom are members of the Society, whose zeal for the science has induced them to undertake the work for the small honorarium which the Council has been able to offer. -A numerous Committee of Publication has been formed, whose Members gratuitously undertake the revision of the proofs and a comparison of the abstracts with the original papers.
The Reports are edited by Mr. Watts, each monthly part being bound up with the corresponding number of the Chemical Society's Journal. Each volume will be furnished with a full index, and will give a complete view of the progress of Chemistry during the year.
The Committee feel that their thanks are due to all those gentlemen engaged in the work for having already so far succeeded in accomplishing a task of such difficulty and importance, and they confidently hope that their continued exertions will still further perfect the details of the scheme so as gradually to increase the usefulness of the Reports.
It is right to state that the funds of the Chemical Society available for the purpose of the Reports, although so opportunely aided by a grant of £100 from the British Association, were insufficient to defray the necessary expenses, and that voluntary contributions to the amount of upwards of