50 CHELONIAIMBRICATA. 



slightly prominent in the centre; the second and third are also hexagonal, with 

 their anterior margins concave and slightly rounded behind to fit the adjoining 

 plates; the fourth is similar in form, but broad before and narrow behind; the fifth 

 is irregularly trapezoid; the first lateral plate is irregularly quadrilateral, longest 

 in the transverse direction, and rounded at its anterior and external margin; the 

 second and third are pentagonal; the fourth is quadrilateral and smaller, with its 

 posterior border smallest; of the marginal plates the nuchal or intermediate is 

 irregularly quadrilateral, extensive transversely, narrow at the middle, and con- 

 cave in front; the first marginal is irregularly triangular, with its external angle 

 curved; the second is quadrilateral, as well as the third, fourth, fifth, sixth and 

 seventh, and more or less elongated; the eighth, ninth, tenth and eleventh have 

 their outer and posterior angles more and more developed and projecting beyond 

 the adjoining plates; the twelfth are trapezoidal, with a deep notch between them, 

 which gives a serrated appearance to the posterior margin of the shell more or less 

 distinct: these plates are all imbricated, and smooth, but in old age they some- 

 times become wrinkled. 



The sternum is large, full, entire in front and behind, but hollow and depressed 

 along the mesial region; the intergular plate is small, triangular, with a rounded 

 base directed forwards; the gulars are irregularly quadrilateral, elongated out- 

 wards and forwards; the brachial are irregularly quadrilateral, large, and most so 

 in the transverse direction, with their anterior and external angles truncated; the 

 pectorals and abdominals are quadrilateral and very extensive, most so trans- 

 versely; the femorals are also broad, but are irregularly quadrilateral, having their 

 posterior and external angles truncated; the subcaudal are irregularly trigonal and 

 elongated; of the supplementary plates the axillary is irregularly pentagonal, the 

 inguinal is quadrilateral, and between these are two quadrilateral or pentagonal 

 plates that unite the abdominal and femoral with the marginal. 



The head is oval, elongated, compressed at the sides, and very narrow in front 

 of the eyes. The upper jaw is greatly prolonged, and hooked anteriorly like the 

 beak of a hawk, from which circumstance the common name of the animal is 



