118 TESTTTDDJID^. 



Var. mexicana. 

 Cistiulo (Uuychotrla) mexicana, Gray, Proc, Zool. Soc. 1849, p. 17, 



pi. ii. 

 iiioxicana, Gray, Cat. Sh. Rc^pt. i. p. 40 (18oo), and Sappl. 



p. r.> (1.S70) ; Bocourt, Miss. Sc. Mex., Rept. p. 17 (1870) ; Gilnth. 



Biol, a- Am., R(pt. p. 1 (188o). 

 Onychotria mexicana, Dwjes, La Naturalcza, 1888, p. — . 



Carapace oval, more tcctiform ; an additional, smaller, vertebral 

 shield between the fourth and fifth ; second costal shield twice as 

 broad as long. Hook of u])per jaw notched, bicuspid, No distinct 

 web between the digits ; only three claws to the hind limb. Cara- 

 pace brown with yellow spots or radiating lines ; plastron variegated 

 brown and yellow. Head uniform yellow above ; limbs brown, 

 with yellow spots. 



Length of shell 17 centini. 



Mexico. 

 «, 6. $,stlfd. Mexico. (Types.) 



2. Cistudo ornata. 



Cistudo ornata, Agassiz, Contr. N. II. U, 8. i. p. 445, pi. iii. figs. 12 

 & 13 (1857;. 



Carapace shoxt, rather depressed, the vertebral region flat and 

 without any keel or ridge, even in the young : shields as in C. 

 Carolina. Plastron not closing completely the shell, connected with 

 the carapace by a very short but distinct bridge. Hook of upper 

 jaw notched. Digits without distinct web. Carapace and plastron 

 dark brown or black, elegantly marked with yellow spots and 

 radiating lines ; a yeUow vertebral line. Head and limbs brownish, 

 with yellow spots. 



Length of shell 12 centim. 



Nebraska, Kansas, Iowa, Missouri, Hlinois. 



a-(l. 2 & yg., spir. Southern Bonn, Kansas. Smithsonian Institution. 

 e. cJ , shell. N. America. 



14. NICORIA. 



Chersine, part., Merrem, Tent. p. 29 (1820). 



Emvs, part., Bum. l*j- Bihr. ii. p. 2.32 (1835) : Gray, Cat. Tort. p. 14 



(1844), and Cat. Sh. Rept. i. p. 19 (1855) ; Gilnth. Rept. Brit. 



hid. p. 21 (1804). 

 Geoemyda, part., Gray, Proc. Zool. Soc. 1834, p. 100, and Cat. Turt. 



p. 14. 

 Nicoria, Gray, Cat. Sh. Rept. i. p. 17, and Snppl. p. 26 (1870). 

 Clemmys, part., Straitch, Clielun. Stud. p. 28 (1802). 

 Rhinoclemmys, Gray, Ann. ^' Mag. N. H. (3) xii. p. 182 (18G3) ; 



and Suppl. Cat. Sh. Rept. i. p. 20. 

 Chelopus, part., Cope, Proc. Ac. Philad, 18G5, p. 185. 

 ]Melauocbelys, Gray, Proc. Zool. Soc. 1869, p. 187, and Suppl. Cat. 



Sh. Rept. i. p. 33. 

 Geoclemmys, part.. Gray, Suppl. Cat. Sh. Rept. i. p. 26. 



Neural plates mostly hexagonal, short-sided behind, or alternately 



