784 EEPTILIA. 



before the anterior extremity of the inguinal valves. The bones of the posterior 

 pairs are thickened over the point from which their median transverse connecting 

 rod diverges inwards. There is a considerable deposit of pigment in these locali- 

 ties, in very young specimens, the whole of the area in the neighbourhood of the 

 second, third, and last pair of the plastral bones being deep black, this colour becom- 

 ing fainter with age ; but it is still present in specimens measuring 4 inches in 

 length. 



In animals 3 inches long, the anterior roughened surfaces are O'^^'SS long. They 

 first make their appearance near the anterior extremities of the epiplastra, and 

 grow outwards as distinct plates beyond the external margins of the epiplastra, their 

 internal borders corresponding to the same border of the bones. The azygos 

 callosity appears on the arch of the entoplastron towards its posterior margin. 

 The lateral callosities first appear on the broad surface formed by the union of the 

 hyo- and hypoplastra, and extends as these bones grow on to the posterior rami 

 of the hypoplastra, above the division, but less so on to their external rami, and 

 hardly reaching their internal rami. The hinder callosities, 0"'35 long in this 

 female, appear on the surface from which the three arms of each xiphiplastron 

 diverge, and gradually extend on to the first and hinder arms, but more so on to the 

 former than on to the latter. These callosities do not extend on to the transverse 

 rami of the hypoplastral bones. 



In examples 4 inches long, the plates of the epiplastra are more or less quadran- 

 gular, separated from each other by two-thirds of their own diameters, while the 

 entoplastral plate is a minute rough crescentic area. The hyo- and hypoplastral rough 

 surfaces have a straight anterior margin, two concave internal margins, one before 

 the other, and one external concave border. The xiphiplastra are rather elongated 

 ovals, separated from each other in their posterior halves by one-half of their 

 own diameters, their anterior halves being strongly divergent. In the fresh state all 

 these callosities are invested with a thin skin. 



In the adult, the skin is thick and fleshy, the granules are round and pearly, and 

 on the inside of the sternum the callous plates are seen to invest the bones with 

 the exception of a short basal portion which permits the epiplastra to move freely 

 on the entoplastron. The development in the epiplastra is most extensive on their 

 posterior ends, the bony plate in that direction being more than twice the size of the 

 anterior section. The entoplastral plate is developed downwards between the two 

 halves of the bone, the ends fit into the lateral plates before their anterior processes 

 and produce a notch in E. punctata. The processes of the hyo- and hypoplastra 

 are wholly and broadly invested by the rough plates, only the extremities of their 

 internal processes remaining free in E. punctata. In adults, the xiphiplastral 

 plates embrace all their bones except their extremities anteriorly and posteriorly, 

 while three of the transverse processes fit into each other side by side, the tip of 

 each abutting against the opposite bony plate when the two halves of the plastron 

 are bent upwards and inwards, so that this motion is very limited, while motion 

 in the opposite direction is very free. 



