00 



Kobert E. Coker. 



marni has observed interplastrals, as abnormalities, at other points, 

 but always at the meeting-point of four plastral scutes. 



Plastrals. 



The plastral scutes (cf. Fig. B) are remarkably constant; only 

 two supernumerary scutes were noted. No. 132 showed an anom- 

 alous scute between the femoral and the anal of the right side (Fig. 

 K), and in No. 233, two scutea occupied on the right side a space 

 equivalent to that occupied by the femoral on the left (Fig. L). 

 No. 88 presented an interesting abnormality discussed in a former 

 paper ('05 a, pp. 14-18 and Fig. 6). In this specimen, the 

 abdominal and femoral scutes were entirely separate to a certain 

 point, but the last three rings of growth were perfectly continuous 

 between the two scutes internally or mesially (Fig. M). 



Fig. H. 



Fig. I, 



Fig. H. Anterior portion of plastron of No. 181, showing small "inter- 

 plastral." 



Fig. I. Part of plastron of a species of Chelodina, showing large "inter- 

 plastral." 



In at least one species of turtle Eretm-oclielys imhricata, the scutes 

 of the shield (Car. and Plas.) are imbricate and are said to be 

 added to anteriorly as they wear away posteriorly. In the carapace 

 of Malaclemmys the scutes are not imbricate, but they grow more in 

 the anterior and lateral directions than in the posterior direction. 

 In the plastron, however, there are often traces of overlapping pos- 

 teriorly, especially in young shells. The posterior part of the rings 

 of growth, usually very narrow, may be particularly so in such 

 specimens, or even entirely wanting, the mesial segments of the 



