DERMATEMYDIDiE. 



239 



Both the carapace and the plastron of this species are ornamented with rows of shallow 

 pits. On the carapace these pits are arranged mostly in rows that run obliquely across the 



costal, neural, and peripheral bones. On the median parts of 

 the plastron the pits are less distinct, but still evidently present. 

 The relationships of this species to A. beatus are discust 

 under the latter species. Figs. 298 and 299, taken from Dr. Wie- 

 land, represent the position of the sulci on the first left peripheral 

 of A. punctatus and A. beatus. From these it appears that the 

 width of the first vertebral scutes was considerably greater in the 

 former than in Leidy's species; also that the free border of the 

 bone itself was wider in Marsh's species than in Leidy's. As 

 regards the width of the front of the vertebral scute, there is 

 I -ii.. iqh. Adocus punctatus. ]j ao i e to De variation in it, and not much stress can be placed 



First left peripheral of type 

 \. After Wieland. 



on it. The specimen in the Philadelphia Academy which the 

 writer is obliged to refer to A . lacer differs from the type in the 

 arrangement of the scutes on the first peripheral. 



Adocus beatus (Leidy). 



Plate 34, figs. 6, 7; text-figs. 299-301 . 



Emyi beatus, Leidy, Cret. Reptiles, U.S., in Smithson. Cont. Knowl., xiv, 1865, pp. 107, 119, plate xviii, 



figs. 1-3. 

 ( - beatus, Cope, Proc. Acad. Nat. Sci. Phila. 1868, p. 235 ; Cook's Geol. New Jersey, 1868 (1869), 



p. 7; ;4; Ext. Batrach., Reptilia, Aves N. A., 1869, pp. 129, 233; Proc. Amer. Philos. Soc, XI, 

 1870, pp. 296, 547; Ibid XII, 1871, p. 43; Vert. Cret. Form. West, 1875, p. 262. Hay, Bibliog. and 

 Cat. Foss. Vert. N. A., 1902, p. 444. 



The type of the present species consists of the anterior half of the first neural, the third and 

 fourth neurals complete, the proximal portions of the second and third costals, the proximal 

 end of the left first costal, and the left first peripheral. These were obtained in the Cretaceous 

 greensand at M ullica Hill, Gloucester County, New Jersey, and were presented to the Academy 

 of Natural Science of Philadelphia, by William M. Gabb. These remains are yet in the 

 Academy's collection. 



In 1869 Professor Cope, as cited, identified as belonging to this species a plastron and 

 some portions of the carapace which had been found in the greensand at Medford, New Jersey. 

 These bones are now in the Cope collection at the American Museum of Natural History, 

 at New York. A figure of this plastron is here presented (plate 34, fig. 6). Besides the 

 greater part of the plastron there are present fragments of several costals, and some anterior 

 peripherals. 



In 1890 Professor O. C. Marsh (Amer. Jour. Sci., XL, p. 178) described A. punctatus. 

 Afterwards Dr. Baur (Proc. Acad. Nat. Sci. Phila. 1891, p. 428) affirmed that this species 

 is identical with Leidy's A. beatus. Now, a comparison of Cope's specimen with the type of A. 

 punctatus shows that they are without doubt of different species. At the same time, it is perhaps 

 impossible to point out characters which will enable us to separate either Cope's or Marsh's 

 specimens from Leidy's imperfect type. In such a case we must do one of three things 

 reject Leidy's species and its name, because of its ambiguous characters, giving a new name to 

 Cope's specimen and retaining Marsh's specific name; accept Baur's conclusion, reducing 

 Marsh's name to synonymy and renaming the Cope specimen; or accept Cope's determination 

 and thereby avoid any new names. Cope's turtle having come from the same region and level, 

 and having been first determined as A. beatus, it appears to the writer that the last of the three 

 courses is the best to follow. The principal respect in which the Medford specimen differs 

 from Leidy's type is in the thickness of the first peripheral. In Leidy's specimen (figs. 299, 

 300) this is only 15 mm. thick, while that of Cope's is 20 mm. This does not, however, decide 

 the question in favor of Baur's position, for the type of./, punctatus also has this bone 20 mm. 

 thick. It is not at all improbable that the shell was thicker in some individuals than in others. 

 Fig. 300 represents the same bone "I Leid) 's type, as the bone appears from below, showing an 

 excavation for a process from the nuchal. 



