18 CTSTUDA. 



The form of the sternum of this genus is very pecuhar, 

 for it is divided across by a cartilaginous suture between the 

 pectoral and abdominal plates; and being only connected to 

 the back shell by a cartilaginous suture, both the anterior 

 and posterior lobes are moveable on the same axis, so as to 

 be capable of entirely closing the cavity of the upper shell, 

 and concealing the inclosed animal from view and danger. 

 The axillary and inguinal shields are small and obscured by 

 the margin ; the marginal plates vary in number from 23 

 to 27, including a distinct nuchal one. This group consists 

 of four species, each found in different parts of the world. 

 The European species, by its depressed form, slightly lobed 

 sternum, and wider symphysis, appears to unite them to the 

 true Emydes. 



This genus forms part of the genus Chtuda of Fleming and 

 Say, and part of Terrapene and Sternotheriis of Mr. Bell. 



1. Cistiida Carolina, [ylmerican Box Terrapin). — Testa 

 subhemispherica fusca luteo-variegataleviter carinata scutellis 

 subsulcatis, marginalibus 23 — 27. Animal nigrum luteo vel 

 aurantio variesjatum. 



Test. Carolina, Lin. Daud. Test, brevicaudata, Lacep, (v. 

 Mus. Par.) Test, invar cerata striata, Bonat. Terrapene Ca- 

 rolina, Bell. (v. Mus. Bell.) Test, clausn, Daud. Cistiida 

 clausa. Say. Test, virgulata Daud. ii. t. 23, (v. Mus. Par.) 

 Test, incarcerata, Bonat. Test, carinata, Lin. Emi/s diihia, 

 Schw. (v. Mus. Par.) Terrapene guttata. Bell, (v. Mus. 

 '&^\\.) Emys Schneideri,'&c\\yN. Edw. t, 20.5, cop. Shaw Zool. 

 iii. t. 7, and Seligman vi. t. 100, and Bechst. Lacep. t. 

 f. — Schoepf. t. 7. — Bloch, Berl. Naturf, t. 1, f, 1, 2. — 

 Grew. t. 3< f. 2. 



Junior, Testa fusca pallide nebulosa, Terrapene nehulosa. 

 Bell, (v. Mus. Bell. Col. Surg.) 



/3. Scutello nuchali nullo (v. Mus. Bell.) 

 Habitat in America Boreali. {v. v. Hort. nost, et Bell.) 

 T have examined and kept several living specimens, and 

 carefully compared the original specimens of most of the 

 above synonyma, and have not been able to separate them 

 from one another ; I beheve that Mr. Bell has himself given 

 up the idea of this species being distinct, since he has been 

 enabled to examine more living specimens. The young are 

 often brown and pale clouded, but the pale spots are placed 

 in the same situations as the yellow spots in the adult spe- 

 cimen, and gradually pass into them. 



