= 
DERMATEMYDID®. 27 
Fam. 3. DERMATEMYDID. 
Steganopodes, part., Wagler, Syst. Amph. 1830. 
Hlodites Cryptodéres, part., Duméril § Bibron, Erp. Gén. ii. 1835. 
Kmydide, part., Gray, Cat. Tort. 1844, and Sh. Rept. i. 1855. 
Chersemyda, part., Strauch, Chelon. Stud. 1862. 
Dermatemyde, Chelydride, part., Gray, Suppl. Cat. Sh. Rept.i. 1870. 
Chelydrine, part., Cope, Proc. Ac. Philad. 1872, p. 22. 
Chelydridee, part., Emydidee, part., Cope, Proc. Amer. Philos. Soc. xx. 
1882, p. 144. 
Staurotypidee, Giinther § Boulenger, “Tortoises,” Encycl. Brit. 1888. 
Dermatemydidee, Bawr, Zool. Anz. 1888, p. 595. 
Nuchal plate produced into costiform processes, underlying the 
marginals. Plastral bones nine. Shell covered with epidermal 
shields. Caudal vertebra proccelous. Neck completely retractile 
within the shell. Temporal region not roofed over ; no parieto- 
squamosal arch. Digits moderately elongate; phalanges with con- 
dyles ; claws four or five. 
This family is intermediate between the Chelydride and the Ci- 
nosternide, agreeing with the former in the presence of the ento- 
plastral bone, and the absence of a symphysial bridge between the 
pubis and ischium, with the latter in the proccelous caudal vertebree. 
In the mode of articulation of the posterior cervical vertebrae, and 
in the development of rib-like transverse processes to the nuchal, 
the three families agree. The Dermatemydide and Cinosternidee 
further agree in the neural plates forming an incomplete series, the 
posterior costals meeting on the median line. 
Externally, the separation of the plastral shields from the mar- 
ginals by the interposition of a series of inframarginals distinguishes 
this family from the Testudinide, and the short tail readily from the 
Chelydride and Platysternide. 
In Dermatemys, the second cervical vertebra is biconvex and all 
the following are proccelous; in Stawrotypus, as in Cinosternum, the 
second is opisthoccelous, the third biconvex, and the rest proccelous. 
The habitat of the Dermatemydide is restricted to Central 
America. 
Synopsis of the Genera. 
I. Plastron large, connected with the carapace by a broad bridge ; 
plastral shields eleven or more; chin without dermal append- 
ENS eee Rs Re ee ee an Seen he aaa 1. Dermatemys, p. 27. 
II. Plastron small, cruciform, with from seven to nine shields ; chin 
with a pair of dermal appendages. 
Plastron joined to carapace by suture .... 2. Staurotypus, p. 29. 
Plastron joined to carapace by ligament .. 3. Claudius, p. 32. 
1. DERMATEMYS. 
Dermatemys, Gray, Proc. Zool. Soc. 1847, p. 55, and Cat. Sh. Rept. i. 
p- 49 (1855), and Suppl. p. 49 (1870); Bocourt, Miss. Se. Mex., 
Rept. p. 17 (1870). 
Chloremys, Gray, Proc. Zool. Soc. 1870, p. 715, and Suppl. Cat. Sh. 
Rept. p. 50. 
