DERMATEMTDID.E. 27 



Fam. 3. DERMATEMYDID^. 



Stop'anopodes, part., ]l'a;/Ier, Sjjsf. Amph. Ls.'iO. 



Eloditt's Cryptoderes, part., Dumeril i^- Biliron, Erp. Gen. ii. 1835. 



Euiydidjo, part., Gray, Cat. Tort. 1844, and Sh. liept. i. 18o5. 



ClifrsGiiiyda, part., Strutich, Chclon. Stud. 1802, 



Dermatemyda^ Chelydridic, part., (rra)/, Suppl. Cat. Sh. Rept. i. 1870. 



Clit'lydriiKe, part., Cope, Proc. Ac. Philad. 1872, p. 22. 



Clielvdrida3, part., Emydida), part., Cope, Pror. Amer. Philos. Soc. xx. 



1882, p. 144. 

 Staiirotypid.T, Giutthcr S,- Bouh')i;/er, "Torfoi.^e.'i,'" Eticycl. Brit. 1888. 

 Dermatemydidaj, Baiir, Zoo/. Anz. 1888, p. 595. 



Nuchal plate produced into costiform processes, underlying tlio 

 marginals. Plastral bones nine. Shell covered with epidermal 

 shields. Caudal vertebra) proccclous. T^eck 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 Chelj'dridte and the Ci- 

 nosternidic, 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 theprocrelous caudal vertebrae. 

 In the mode of articulation of the posterior cervical vertebrte, and 

 in the development of rib-like transverse processes to the nuchal, 

 the three families agree. The Dermatemydidae and Cinosternida3 

 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 Testudinida?, and the short tail readily from the 

 Chelydridse and Platysternidas. 



In Dermatem'i/s, the second cervical vertebra is biconvex and all 

 the following are procoelous ; in Stcnirotr/pus, as in Cinostermim, the 

 second is opisthocoelous, the third biconvex, and the rest procoelous. 



The habitat of the Dermatemydidae 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- 

 ages 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. Staiirotypus, 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. Rcpt. i. 



p. 49 (1855), and Suppl. p. 49 (1870) ; Boconrt, Miss. Sc. Mex., 



Rept. p. 17 (1870). 

 Chloremys, Gray, Proc. Zool Soc. 1870, p. 715, and Suppl. Cat. Sh. 



Rept. p. 50. 



