88 EMYS TERRAPIN. 



vertebral plates has a protuberance; that of the fourth is the most prominent; 

 these tubercles, taken together, give an obtusely carinated appearance to the shell 

 — some varieties have the prominences but slightly developed. Of the lateral 

 plates, the anterior is irregularly quadrilateral, largest at its lower and anterior 

 border, where it is joined to four margmal plates; the second and third are pen- 

 tagonal; and the fourth very irregularly quadrilateral. The marginal plates are 

 twenty-five in number; the nuchal, or mtermediate, varies in shape — sometimes 

 triangular, with its apex truncate and directed anteriorly; at others it is almost 

 quadrilateral; the remaining marginal plates are nearly quadrilateral; the five 

 posterior are slightly revolute, and thus form at times a sort of gutter. 



The sternum is sub-oval, entire in front, and extending even as far as the shell; 

 it is emarginate behind, does not reach the length of the carapace, and is covered 

 with twelve plates marked with concentric strise. The gular plates are triangular, 

 with their apices directed barkward; the brachial are nearly quadrilateral, the 

 lateral margins most extensive; the thoracic and abdominal plates are oblong 

 squares, and the sub-caudal lozenge-shaped. Of the supplemental plates, the 

 axillary are irregularly quadrilateral and broadest before, while the inguinal are 

 triangular and broadest behind. 



■&^ 



The head is very large, broadest posteriorly, narrow, and almost pointed in 

 front; above, it presents a smooth surface, as if the head were covered with a 

 single large rhomboidal plate, differing in some degree in colour from the rest of 

 the animal. The jaws are strong and cutting, the superior slightly emarginate; 

 the inferior curved in front, and furnished with a hook. The eyes are small, the 

 pupil black, the iris gray, approaching the colour of the skm. The neck is short 

 and thick. 



The anterior extremities are moderately long, and scaly before; scaly and 

 granulate behind; the fingers are five in number, webbed, and each furnished with 

 a short strong nail. The posterior extremities are rounded above, but flattened at 

 the tarsus; scaly in front and granulate behind; there are five toes, fully webbed. 



