56 EMYSCUMBERLANDENSIS. 



the intermediate or nuchal is an oblong square, a little rounded and projecting an- 

 teriorly; the first marginal is pentagonal, dentated in front, its external point most 

 prominent, reaching beyond the second plate; these three plates give the notched 

 appearance to the anterior margin of the shell; the second marginal is quadrilateral, 

 and broadest in front; the remaining plates are all quadrilateral; the fourth, fifth, 

 sixth and seventh regularly so, with their external margins slightly revolute; the 

 eighth, ninth, tenth, eleventh and twelfth marginals are all notched in the centre 

 of their outer borders; the eighth least, and the twelfth most deeply; these notches, 

 as well as the projection of the posterior and external angle of each plate, give 

 the beautiful serrated margin already mentioned. The marginal plates are marked 

 near their upper border with two or three slight concentric lines; all these lines 

 on the marginal, as well as on the vertebral and lateral plates, disappear with 

 age, and the shell becomes perfectly smooth. 



The sternum is large, full, entire and rounded in front, and truncated behind; the 

 gular plates are regularly triangular, with their bases before and their apices 

 behind; at their anterior and external angles is a remarkable tooth or process, 

 extending forwards and upwards; the brachial plates are also triangular, with 

 their bases outwards, and their apices inwards and truncated; the thoracics are 

 oblong-quadrilateral, and the abdominals pentagonal and broad; the femoral plates 

 are irregularly quadrilateral, rounded and large without, narrow and straight 

 within; the subcaudals are triangular, with rounded bases directed posteriorly; 

 the supplemental plates are two in number on each side; the axillary is triangular 

 and large, with its basis forwards; the inguinal is also large, oblong, round behind, 

 and pointed before. 



The head is small; the snout short and rather pointed; the nostrils are anterior 

 and closely approximated; the upper jaw has a thin cutting border, slightly emar- 

 ginate in front, and the lower is furnished with a small hook; the eyes are bright; 

 the pupil black; the iris golden, with a black spot before and behind the pupil; the 

 neck is rather long and slender. 



