presents his geological views and criticisms with great positiveness, which is consistent with the fact of his limited knowledge of the subject.

8. Geological Survey of Iowa.-The State of Iowa has ordered the printing of three thousand copies of the Report of the Geology of the State by Prof. White. The work will consist of two royal octavo volumes, in the style of Hall's Geology of Iowa and of the Illinois Geological Report, and will be well illustrated. We regret to have to add that the Legislature has discontinued the Survey.

III. ZOOLOGY.

1. Die bis jetzt bekannten Schildkröten, u. d. bei Kelheim u. Hannover neu aufgefunden altesten Arten derselben; von Dr. G. A. MAACK. Cambridge, Mass. (Cassel, 1869,-from H. von Meyer's Palæontographica).-This useful work, a 4to of 146 pp., is contributed by Dr. Maack, whose arrival in the United States and occupation in the Museum of Comparative Zoology, we take pleasure in noticing. It embraces a synopsis of the species of extinct Testudinata, arranged in the order of geological succession, rather than according to structural affinity. The number thus enumerated is 192, of which 26 are assigned to the Testudinidæ, 114 to the Emydidæ, including the Pleurodira; 27 to the Trionychidæ, and 25 to the Cheloniidae. The species are not nearly all described, but their enumeration forms an invaluable hand-book to the student of the subject. The stratigraphical table given, adds to its value. From it we perceive that the Tertiaries embrace the majority of the species, and the Cretaceous and Jurassic periods successively fewer. The upper Jurassic of Switzerland, Bavaria and Hanover have furnished the oldest known Testidinata, unless the Chelytherium of the Würtembergian Trias belong to the order, a point still doubtful. The number of Jurassic species known was 15, to which Dr. Maack adds 3, based on remains mostly from Hanover, from a stratum of prior deposit to those of Switzerland and Bavaria.

Before noticing the types of Cretaceous and Jurassic Tortoises, it must be observed that the system of Strach which Dr. Maack adopts, is a very defective one, and far behind the requirements of modern zoology and paleontology. The structural features defining the suborders and families are overlooked in this. For example, one of the primary divisions of the order, the Pleurodira, is included among the Emydidae, whereas it embraces a series of families distinguished by features quite similar to those defining the remaining families from each other.* In consequence several conclusions are reached which require modification. The genus Platemys as adopted may be cited. It embraces 9 species according to the present work, the genus Pleurosternum of Owen being referred to it. This is done because the additional pair of thoracic bones which characterizes it is found in a rudimental

See Proc. Acad. Nat. Sci., 1868, p. 282.

condition in Platemys Bowerbankii, and Platemys Bullockii of Owen presents the intermarginal scuta of Pleurosternum, and because of the general resemblance in specific characters between the latter and the Pl. concinnum. To us, however, the genus Pleurosternum appears to be Cryptodire not Pleurodire, as it lacks. the integular scutum of the latter suborder, and to represent a peculiar family of that group characterized by the possession of ten instead of eight sternal bones. Platemys Bullockii, P. Bowerbankii and Emys lavis Ow. and Bell appear on the other hand to be Pleurodira, and to be referable to two families of that suborder. The Pl. Bullockii, on account of its five pairs of sternal bones, to the Sternothæridæ, and on account of its intermarginal scuta, to a new genus which I have called Digerrhum. The last two, in their rudimental fifth pair of sternals resemble many Pleurodira, and cannot be distinguished from the genus Podocnemis now living in the Amazon. The P. sulcatus Leidy is near to Podocnemis also, but represents a distinct genus, characteristic of the Cretaceous, which I call Taphrosphys; there are six species in North America. After these deductions the only Platemydes that remain are P. Mantellii and P. Dixonii of Owen.

The new forms described by Maack are of much interest. His Chelonides Wittei is one of the group found in both Jurassic and Cretaceous strata in Europe and North America, which combines Chelydroid and Chelonioid characters so as to render it difficult to be assured as to which group they truly represent. The characters of the carapace in most, and of the plastron in many, are those of the latter, while those of the limbs, the crucial test in this case, are those of the former. Two of the North American genera add one or two costal bones, a character of importance and one not hitherto met with in the order; these may be regarded as the type of a peculiar family with the name of the Propleurida, including the genera Osteopygis and Propleura. The family with eight costals includes Chelonides Maack, which seems to be near Chelonemys Jourd, as he has placed it,-with Platychelys, Hydropelta, Idiochelys and some other European forms which, with Catapleura and Lytoloma from North America, are nearer Chelydra, and I cannot at present find characters which distinguish them as a family from the existing forms. In Stylemys Maack, the second new genus introduced into the present work, the sternum is without fontanelles, and resembles entirely that of Adocus from the American Cretaceous, while the carapace and femur are of the type of Osteopygis. Until further investigated it should remain as an Emydoid, as placed by Dr. Maack. Two species are described, S. Lindenensis and S. Hannoveranus. The use of the name Stylemys is a faux pas, since it must probably be used for a genus of Emydido described by Leidy from the Miocene and Pliocene of Nebraska and Dakota. True, it was originally established on untenable characters, and reunited by its proposer with Testudo. But I have been able to point out (Trans. Amer. Phil. Soc., 1869, 123) that the species so originally named are really Emydido

having Testudinine characters, and requiring a distinct generic name, for which Stylemys should perhaps be adopted. Dr. Maack will therefore be necessitated to find another for that which he describes.

This and other rectifications relating to North American species not having been published prior to Dr. Maack's work, he was unable to take advantage of them. I therefore append the fol lowing list as supplementary to it.

Thirty-eight species. Puppigerus embraces all of the Chelones described by Owen and Bell from Sheppey. To Lytoloma perhaps belong the two Chelones described and figured by Faujâs and Cuvier from the Cretaceous of Maestricht named Ch. cretacea by Keferstein and Ch. Faujasii by Maack.

E. D. C.

2. On Discosaurus and its allies; by Dr. J. LEIDY. (Proc. Acad. Nat. Sci. Philad., 1870, p. 18).-On the 5th of April, Dr. Leidy made remarks on Discosaurus and its allies, additional to those published at p. 392 of the last volume of this Journal; and in the course of it discusses the relations of Cimoliasaurus, as originally established, to Discosaurus. On this point he observes:

"In the first place, by comparison with the skeleton of the Kansas saurian, we observe that the position in the column assigned to the vertebral bodies of Cimoliasaurus was incorrect, and this probably contributed to mislead Prof. Cope in his examination of the skeleton of the Kansas saurian.

"The vertebral specimens referred to Cimoliasaurus consisted of two sets of specimens, from two different individuals, both from the greensand of Burlington Co., N. J. They are described in Cretaceous Reptiles,' page 25, and characteristic ones presented in plates v and vi.

The eleven vertebræ considered as lumbar, and represented by figs. 17-19, pl. v, and 16-18, pl. vi, are evidently cervicals. Those considered as dorsals on page 26, and represented in figs. 13-16, pl. v, are at least in part posterior cervicals. Of the fourteen vertebræ referred to on page 27 as dorsals and lumbars, those described and represented in figs. 1-5, pl. vi, are alone dorsals, while the others described and represented in figs. 6-9 are posterior, and those of figs. 10-18 more anterior cervicals.

"The cervicals of Cimoliasaurus are so different in their proportions from those of the Kansas saurian that there can be no question as to the distinction of the two animals, at least as species.

"Do all the remains originally referred to Discosaurus belong to this genus as distinct from Cimoliasaurus? I suspect that those from New Jersey belong to the latter. The animals indicated by all the fossils which have been under consideration are Plesiosauroid, and, as in recognized species of Plesiosaurus, there is much variability in the number, proportions, and other characters of the cervicals without a corresponding extent of variation in other parts of the vertebral column, we would be prepared to find in Cimoliasaurus nearly the same kind of caudals as in Discosaurus.

"Prof. Cope, in his Synopsis of the Extinct Batrachia and Reptilia,' pt. i, 1869, p. 56, describes two vertebral specimens from the lower bed of the Cretaceous green sand of Gloucester and Monmouth counties, which he attributes to a species with the name of Elasmosaurus orientalis. The specimens described as caudals are seen, by comparison with the Kansas skeleton, to be cervicals."

The species referred to in this paper-all Cretaceous-are finally as follows: 1. Discosaurus vetustus Leidy (Cimoliasaurus magnus, and C. vetustus, of Cope), from Alabama. 2. Disc. grandis (Bri

mosaurus grandis Leidy, Cim. grandis Cope), from Arkansas. 3. Disc. carinatus (Elasm. platyurus, and Disc. carinatus of Cope) from Kansas. 4. Disc. magnus (Cim. magnus Leidy, Disc. vetustus in part? Leidy), from New Jersey. 5. Disc. planior (Disc. vetustus in part, Leidy), from Mississippi. 6. Disc. orientalis (Elasm. orientalis Cope), from New Jersey.

rus.

3. On Elasmosaurus platyurus Cope; by Prof. E. D. COPE. (Communicated by the author).-I observe, in the last number of this Journal, that Prof. J. Leidy criticizes my determination of the structural characters and generic relationships of the above reptile, stating that I have reversed the direction of the vertebral column, describing the cervical as the caudal series and vice versa, and that it is the same as his previously described genus DiscosauOn these points I would make the following observations. First, as to the direction of the vertebral column, I have little doubt that Prof. Leidy is correct in his determination, especially since I have already pointed out, that, assuming the direction I gave it to be true, the vertebral articulations, and the scapular and pelvic arches, appeared to be the reverse of those of Plesiosaurus. Prof. Leidy does not, however, allude to the principal cause of this error, which was the similar reversal of the vertebral column in his descriptions of his genus Cimoliasaurus, first published in 1851, and re-published with 2 plates in 1864. Having my mind pre-occupied with this determination and not suspecting the error, I arranged Elasmosaurus in accordance with it. The great size of the clavicle, and lack of special characters of the scapular arch, as mesosternal, etc., and consequent close resemblance to many reptilian fishes, rendered the error more easy, while the coincident discovery of several reptilian forms with zygosphene articulation, attracted my atention to that character.

It might be added that the description and restoration are correct in the "Synopsis Extinct Batr. Reptilia, etc., North America," the error having appeared in a few extra copies only. Also that the accounts already given will require scarcely any modification, the caudal region like the cervical being very long, and less depressed than in Cimoliasaurus, etc.

Second, from the identification of Elasmosaurus with Discosaurus, I entirely dissent. Dr. Leidy, having assumed the cervicals of Cimoliasaurus to be lumbars, and stating it as "probable that part of the series described as lumbars may be regarded as representing sacrals and caudals,' "* referred the true caudals of the same genus, to another supposed genus, under the name of Discosaurus. Anterior caudals of Cimoliasaurus magnus he regarded as cervicals of the new genus. But, entertaining a suspicion that the two genera might be one, he says that in this case, they "represent cervicals, dorsals and lumbars of Discosaurus," (i. e. Cimoliasaurus, the name earliest given). Having shown the identity of the two forms in accordance with the structure of Elasmosaurus, I failed to reverse the arrangement adopted by Prof. Leidy. Had I

Cretaceous Reptiles, N. America, 29.