CHELYDRID^. 



19 



The following figure refers to the terminology of the epidermal 

 shields of the shell. 



Fig. 2. 



A. Carapace. 



a. Abdominal. 

 an. Anal. 

 c. Costal. 

 /. Femoral. 

 g. Gular. 



Chelone my das. 



h. Humeral. 

 ig. Intergular. 

 im. Inframarginal. 

 m. Marginal. 



B. Plastron. 



n. Nuchal. 



p. Pectoral. 



sc. Supracaudal. 



I'. Vertebral. 



Fam. 2. CHELYDRID^. 



EmydidiB, part., Gray, Ann. Phil. (2) x. 1825. 



Emydidje, part., Bell, Zool. Journ. iii. 1828. 



Steganopodes, part., WagUr, Syst. A7nph. 18-30. 



Emydse, part., Gray, Syn. Rept. 1831, 



Elodites Cryptoderes, part., Dunieril Sf Bibron, Erp. Gen. ii. 1835. 



Emydidfe, part., Gray, Cat. Tort. 1844, and Sh. Rept. i. 18oo. 



Chelydroidse, Aga-ssiz, Contr. X. H. U. S. i. 1857. 



Chersemyda, part., Strauc/i, Chelon. Stud. 1862. 



Chelydridas, part., Gray, Suppl. Cat. Sh. Rept. i. 1870. 



ChelydrinfB, part., Cope, Proc. Ac. Philad. 1872, p. 22. 



Chelydridse, pajt., Cope, Proc. Am. Philos. Soc. xx. 1882, p. 144. 



Nuchal plate with long costiform processes, underlying the mar- 

 ginals. Plastral bones nine. Shell covered with epidermal shields. 

 Caudal vertebrae mostly opisthoccelous. Neck completely retractile 



D 



