ON THE SKELETON OF TOXOCHELYS LATIREMIS. 

 O. P. HAY. PH.D. 



The genus Toxochelys, having as its type T. latiremis, was origi- 

 nally described by Professor E. D. Cope in the Proceedings of the 

 Academy of Natural Sciences of Philadelphia for 1873, page 10. In 

 the year 1875 the same author, in his Cretaceous Vertebrata, p. 98, 

 pi. viii. figs, i and 2, vol. n, U. S. Geol. Survey, further described 

 the original species and (op. cit. p. 299) a new one under the name 

 of T. serrifer. Of T. latiremis Professor Cope possessed only a por- 

 tion of a lower jaw and the coracoid, which he figured, and some of 

 the phalanges. Of T. serrifer the materials were somewhat ampler, 

 consisting of some skull bones and two marginals; but none of these 

 were figured. In the Proceedings of the American Philosophical 

 Society for 1877, p. 176, Professor Cope gave descriptions of two skulls 

 of T. latiremis which had by this time come into his hands. From 

 these, Professor Cope came to the conclusion that the general form of 

 the skull was much like that of some of the Trionychida, but that from 

 this family Toxochelys was separated by the possession of marginal 

 bones and the character of the extremities. Before this, however, in 

 his description of T. serrifer, Professor Cope had regarded the genus 

 as having relationships with the Cheloniidce and the Chelydrida. In 

 his description of T. latiremis in the same work he had spoken of the 

 phalanges as being flattened, as in Protostega. As will be observed 

 during the discussion of the skeleton of this genus, I conclude that it 

 is related to Cheloniidce and Chelydridce, and not at all to the Triony- 

 chidce. 



The materials in my hands consist of a single skull of T. latir- 

 emis, whose length from the snout to the occipital condyle is close to 

 115 mm. The distance from the alveolar border to the condyle of 

 the quadrate is about 105 mm. The length of the lower jaw described 

 and figured by Professor Cope was 157 mm; so that it must have be- 

 longed to a skull having a length from snout to condyle of about 

 170 mm. 



The skull in my hands has been broken across the middle, and 

 some parts of the roof of the mouth are missing; but nothing essential 

 for our understanding of the structure. The damage to the upper por- 



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