134 STERNOTH^RUS ODORATUS. 



Sternothasrus odoratus, et Boscii, Bell, Zool. Jour., vol. ii. p. 307, 308. 



Kinosternon odoratum, Gray, Syn. Rept, p. 55. 



Emys odorata, Harlan, Med. and Phys. Res., p. 156. 



Staurotypus odoratus, Dumeril et Bibron, Hist. Nat. des Rept., torn. ii. p. 35S. 



Musk tortoise, or mud tortoise, Vulgo. 



Description. The shell is oblong-oval in fonn, entire, gibbous, more or less 

 carinate and compressed at the sides. Of the five vertebral plates, the anterior is 

 very long, narrow, triangular, with its basis down and its apex upwards and 

 truncate; the second, third and fourth are hexagonal, with their lateral borders 

 acuminate where they join the lateral plates, the two latter with their anterior 

 borders concave and their posterior rounded; the fifth vertebral plate is pen- 

 tagonal, narrow above and broader below: all these plates are more or less 

 imbricate posteriorly. The anterior lateral plate is quadrilateral, smaller above, 

 large and rounded below; the second, third and fourth are pentagonal, the latter 

 very irregularly so. There are twenty-three marginal plates; the intermediate, or 

 nuchal, is nearly triangular, and extremely small; the remaining plates, to the tenth, 

 are oblong-quadrilateral, this and the eleventh are regularly quadrilateral. All 

 these plates are separated from the shell by a groove, more or less distinct, as far 

 as the two last on each side, which are closely united to the posterior lateral and 

 posterior vertebral plates. 



The sternum is very small, compared with the shell, and is oblong-oval, romided 

 in front, and very deeply emarginate behind. The gular plates are consolidated 

 into one, which is small and triangular, with its apex directed backwards; the 

 brachial plates are also small, triangular, and project beyond the thoracic at their 

 outer and posterior angles. The thoracic are quadrilateral, and joined to the 

 abdominal by a ligamentous substance, to allow certain motions, but far less even 

 than in the Kinosternon Pennsylvanicum; and in very old animals this joint at 

 times becomes anchylosed, and motion ceases. The abdominal plates are quadri- 

 lateral, largest and firmest of all, and are so closely joined to the shell as to admit 

 of but httle if any motion. The femoral vary a good deal: sometimes they are 



