longitudinally-cleaved mass of this mineral, having at one end the cleavage prisms diverging, losing their edges, and slightly branching; strikingly resembling the case figured in our first memoir,* and reminding us of the example of the "canal system," described by Dr. Carpenter as "consisting of parallel lamellæ disposed like the leaves of a book."

Since it was first announced that we had determined "Eozoon canadense" to be nothing more than a mineral production, we have all along felt that specimens would be found demonstrating more and more completely the truth of our conclusion: but we were certainly not prepared to meet with a large crystal of spinel, holding in its chinks and cavities typical examples of two of the essential features of this reputed organism: and these themselves possessing evidences indisputably testifying to their purely crystalline origin.

The Aker and Amity specimens show, what we have long suspected, as intimated here and there in the preceding paper, that the arborescent forms ("canal system") may consist of other silicates besides serpentine. As to their being composed of anything else than a siliceous substance, we are not yet prepared to offer an opinion on the matter; though it must not be overlooked that similar forms, but on a comparatively gigantic scale, are common, consisting of carbonate of lime, in magnesian limestone, near Sunderland, in Durham. We have been led into this subject from observing a recent announcement, by Dr. Sterry Hunt, of another discovery in "Eozoon canadense" (at Chelmsford, near Lowell, U. S.) of "the canals and tubuli of the calcareous skeleton filled, not with a silicate, but with carbonate of lime." On seeing this announcement, we immediately wrote to Mr. Bicknell, of Salem, mentioned by Dr. Sterry Hunt, asking him to oblige us with specimens of the kind. Shortly afterwards we'received from Mr. Bicknell, by sample post, a transparent section carefully prepared by himself, and a piece of the rock,—both labelled "Chelmsford." There were also specimens of "eozoonal" ophite from Newberryport, a neighboring locality. In the latter, some of the structures are typically exhibited: the fibers of the "nummuline layer," however, are more confusedly arranged, and much longer than usual. In the former, the serpentine, of a pale-greenish color, is in irregularly fractured pieces, separated from one another by unusually wide interspaces of calcite ("calcareous skeleton,") which contains bundles of radiating crystals, also groups of vermicular branching forms ("canals and tubuli"): the "nummuline layer" is not well developed, heing often represented by minute radiating aciculi. We have carefully tested the Chelmsford specimens, both by chemical reactions and polarized light, without however, detecting any evidence of the "canal system" being else than siliceous; or of being composed of a substance identical with or related to its "Quarterly Journal of Geological Society," vol. xxii, Pl XV, fig. 17, b. "Intellectual Observer," vol. vii, p. 294.

"Scientific Opinion," January 20, 1870, p. 45.

AM. JOUR. SCI-THIRD SERIES, VOL. I, No. 1.—JAN., 1871.

calcareous matrix.* Now, we cannot dispute the statement of Dr. Sterry Hunt; as probably some mistake may have been made in our specimens. We must, however, in this case too, complain of the very meagre and unsatisfactory account given of the "canals and tubuli" in the otherwise more detailed notice of the Chelmsford "Eozoon," published in the Am. Journ. of Sci., p. 77, of January last. No evidence whatever is offered to show by what process the chemical nature of these parts was determined;-whether the conclusion that they are of the same composition as the "calcareous skeleton" was based on an examination by polarized light; or whether they do not consist of some soluble silica, or of a mixture of a carbonate and a silicate such as would be quite as readily acted upon by weak acid as their imbedding substance, especially if it be dolomite. We wish to call particular attention to the last point, as brief mention has already been made of a specimen of elæolite (a translucent variety, from Brevig), which, in consequence of its being an alkaliferous silicate of alumina (and there is no reason why such a compound may not occur in the Laurentian metamorphic marbles), was dissolved in weak acid. Another specimen, which we have lately subjected to the same process, was taken out of the solution in a partially digested state. When examined with the microscope, the residuum, which is in a slightly coherent condition, was found to consist of interlacing configurations, some of which, where well separated from the rest, bore no inconsiderable resemblance to the "canal system"-not, it is true, in its beautiful arborescent forms, but in the small crooked branching varieties, common to many Canadian examples. Prismatic cleavage, which elæolite eminently possesses, had evidently favored the development of the configurations. They are transparent, rudely branching and anastomosing, showing rarely any cleavage edges or planes; these for the most part having been emoved by the action of the acid.

Such a case as this clearly necessitates every point being duly considered before any conclusion can be drawn as to the chemical nature of the "canals and tubuli," should they appear not to have their ordinary composition. It also strikingly illustrates the view we have taken that these parts in typical "Eozoon" are merely the skeletons of fragments, or of crystals-respectively of serpentine or some other silicate-which remain after their waste had been arrested through changed conditions. Moreover, it testifies to our having succeeded in forming from elæolite, by the action of a weak solvent, configurations approximating to the rude varieties of the "canal system."

3. Scientific Expedition to the Rocky Mountains.-The Yale College scientific party, in charge of Professor O. C. MARSH, which left New Haven in June last for the Rocky Mountains, returned to this city on the 18th of December. The party, which was essentially a private one, consisted of Professor Marsh and twelve com

*We expect still to receive specimens, undoubtedly identical with those described by Dr. Sterry Hunt; when we hope to announce with more certainty the result of our investigations.

panions, all students or recent graduates of the College. The main object of the Expedition was to investigate the extinct vertebrate fauna of the Tertiary and Cretaceous deposits of the Rocky Mountain country, and the general plan adopted was to make several separate trips, of one or two hundred miles north or south of the Pacific railroad, to regions that were unexplored, or had never been carefully examined.

The first of these was made early in July, from Fort McPherson in Nebraska, to explore the Pliocene deposits along the Loup Fork river. Here rich collections of fossil vertebrates were obtained, and several new species of extinct mammals and birds discovered. The next expedition was made in August, from Fort D. A. Russell in Wyoming, to examine the geology of the country between the North and South branches of the Platte river. On this trip the Mauvaises Terres or "Bad land" formation, with the true Titanotherium and Oreodon beds was discovered in Colorado,* and traced northward through Nebraska to the North Platte. The fossil remains obtained were also important, and included several species of extinct mammals and birds, new to science.

The third expedition was made from Fort Bridger, Wyoming, in September and October, to examine the geology of the Eastern Uintah Mountains, and the country between the Green and White rivers. In this region interesting geological discoveries were made, and many new Tertiary vertebrate remains secured, which will soon be described by Professor Marsh. On their return, the party went to California, and spent a month in visiting various points of scientific interest; after which they came east to Denver, and thence to Fort Wallace in Kansas. About two weeks were spent in exploring the Cretaceous beds of this vicinity, where some interesting reptilian and fish remains were obtained, and the party then re

turned to the east.

The Expedition as a whole was very successful, and the large collections made will be placed in the Peabody Museum of Yale College. The more important scientific results will soon be published.

4. Monograph of the North American Astacido; by Dr. H. A. HAGEN. No. III of the Illustrated Catalogue of the Museum of Comparative Zoology. Cambridge, 1870.—Our American crawfish have been much neglected, never having been subjected to thorough study, and, as might be expected, Dr. Hagen has given us an accurate and very valuable monograph. The investigation of the constancy of the specific characters and the sexual peculiarities are highly interesting and form the most important feature of the work. In Cambarus, which includes all the species east of the Rocky Mts., the author has found that the first abdominal legs of the male present great and very constant specific differences,. similar to those discovered in Callinectes by Ordway, and to those in some species of Achelous and Cardiosoma. In this same genus two forms of males are described,-ordinary fully developed in

*This Journal, II, vol. 1, p. 292, Sept., 1870.

dividuals, and a second form in which the individuals retain many of the features of the young and are supposed to be sterile. While the second form of males was found in every species of Cambarus of which any number of specimens were examined, it was found in none of the species of Astacus. This important discovery of dimorphism in the males of Cambarus is accredited to Prof. Agassiz. It is mentioned that perhaps the "fact of the existence in the Crustacea of two forms, one always sterile, is not unique," and a short account of dimorphism in other Crustacea and in insects is given. Among the decapods, the author notices the occurrence of sterile females in "Lupa and Callinectes," and states that he has "found similar females with a narrower triangular abdomen in some other genera of Brachyura." The occurrence of dimorphic sterile females is much more common among the Brachyura than this would imply. DeHaan mentions and figures such forms in several species of Portunids, and the writer has noticed them in Neptunus, Acheloüs, Epilobocera, and Pinnotheres. In all these cases the abdominal appendages are more or less rudimentary and not well adapted for the attachment of eggs.

Thirty-two species of Cambarus and six of Astacus are described, and eleven species, all Cambari are new. The description of the species is followed by an extended account of their geographical distribution. The author remarks on the absence of crawfish in central and eastern New England and the eastern portion of British America, and does not seem to have been aware of their occurrence in the St. Johns and Aroostook rivers.*

The eleven plates contain figures of the first abdominal legs of the male and some other parts of nearly all the species, from the author's drawings, and beautifully executed figures of the entire animals of eight species.

S. I. S.

5. Preliminary Report on the Crustacea dredged in the Gulf Stream in the Straits of Florida; by L. F. de POURTALES, Assist. U. S. Coast Survey. PART I, Brachyura; prepared by Dr. WILLLIAM STIMPSON. Bulletin of the Museum of Comp. Zool., vol. ii, No. 2. 52 pp. Cambridge, Dec., 1870.-In this important paper, Dr. Stimpson gives a full list of the Brachyura collected by the Coast Survey dredging expeditions of 1867-8-9. 81 species, representing 47 genera, are mentioned, and 52 of the species and 19 of the genera are described as new. More than half the species belong to the Maioidea, while the Ocypodoidea are represented by only two species, both of them belonging to the Carcinoplacida. Only a small proportion of the species are from great depths, and the number of new forms seems largely due to the thorough exploration of the shallower waters. But 15 species are recorded as coming from below 100 fathoms, and of these 11 are Maioids, and the other 4 are Cancroids-a Pilumnus, 2 species of Bathynectes (a new genus allied to Portunus) and a species of Achelous. The

*Reports on the Natural History and Geology of Maine. In the Museum of Yale College, there are specimens of Cambarus propinquus from Montreal and from Madison, Wisc.

greatest depth at which any of the species were found is 150 fathoms; and it is quite remarkable that the only species from that depth were Portunidae-one of the species of Bathynectes and the Achelous.

S. I. S.

6. On the Mineral Constituents of Meteorites; by N. S. MASKELYNE, M.A., Prof. Min. Oxford, and Brit. Mus. (Trans. Roy. Soc., 1870).-Mr. Maskelyne takes up in this paper the analysis of the Busti aerolite of 1852. He finds in it the compound, mono-sulphide of calcium, in small spherules of pale chestnutbrown color, and transparent when pure, to which he gave the name Oldhamite in 1862; and minute golden-yellow octahedrons (isometric) named Osbornite. The amount of the latter obtained for analysis was too small for completed results; but led to the conclusion that it contains sulphur, calcium and some titanium-like metal, not titanium or zirconium, with a trace of iron. It is infusible, and not acted on by boiling nitric acid, and, heated in a current of dry oxygen, it undergoes only an external oxidation. Mr. Maskelyne calls attention to observations of Prof. Mallett on a gold-yellow incrustation obtained by heating zirconium with lime and aluminum, contained in this Journal, II, xxviii, 346.

The other constitutents of the aërolite were a magnesian enstatite the main part, augite, schreibersite, nickeliferous iron, and a very small proportion of troilite (FeS) and chromite. The augite is a magnesia-lime augite.

The Manegaum meteorite, which fell in 1843, was found by Mr. Maskelyne to consist of a single silicate, and that enstatite; the enstatite is a highly ferriferous variety, containing

Si 53.63, Fe 20.48, Mg 23·32, Ĉa 1:49, Fe Ër 1·03 =

= 99.95.

This meteorite contains only a minute amount of meteoric iron. The investigations show that the flocculent opaque white mineral seen in the microscopic sections of many meteorites is often, if not always, enstatite.

7. Fossil Mammals of the Rocky Mountains collected by Dr. Hayden; Dr. LEIDY, (Proc. Acad. Nat. Sci. of Philadelphia, Oct. 4-18).-Dr. Leidy here brings out many new facts with regard to the Tertiary Mammalian life of this Continent.

On the Sweet Water river, eighteen miles west of Devil's Gate, Wyoming Terr., the bones are mostly of a species of Merycochorus, smaller than M. proprius; but with these there are remains of an equine animal, perhaps a Hipparion, and of Canis vafer and Merycodus necatus, species first described from the Niobrara.

From Fort Bridger there is a molar of apparently a small species of Lophiodon; part of a lower jaw of a pachyderm, which is named provisionally Hyopsodus paulus; an animal allied to Chalicotherium and Titanotherium, which Dr. Leidy named Palæosyops paludosus, (other specimens of which have been received from Henry's Fork of Green river, Wyoming; a species related to the Peccary, named Microsus cuspidatus; and one related to the Raccoon, named Notharctus tenebrosus.

8. Fossil Mammals from Oregon; J. LEIDY, (ib.). --The specimens were from Rev. Thos. Condon of Dalles City, Oregon. Dr.