40 CHELONIA IMBRICATA. 



and 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 shortest; of the marginal plates, the nuchal, or intermediate, is 

 irregularly quadrilateral, extensive transversely, narrow at the middle, and concave 

 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, nhith, tenth and eleventh liave their outer 

 and posterior angles more and more developed, and projecting beyond the adjoin- 

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

 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- 

 tunes become wrinkled. 



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

 along the mesial region; the inter-gular plate is small, triangular, with a rounded 

 base directed forwards; the gular are irregularly quadrilateral, elongated outwards 

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

 transverse direction, Avith their anterior and external angles truncated; the thoracic 

 and abdominal are quadrilateral and very extensive, most so transversely; the 

 femoral are also broad, but are irregularly quadrilateral, having their posterior 

 and external angles truncated; the sub-caudal are irregularly trigonal and elon- 

 gated; of the supplemental 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 



