Diversity in the Scutes of Clielonia. 



23 



rings ending abruptly at the posterior margin which overlaps the 

 next scute. The overlapping was particularly striking in ISTo. 50, 



ISTo. 145 was characterized by marked asymmetry of abdominal 

 and femoral scutes (Figs. 37, 38, PI. IX). 



Mm^ginals. 

 Except in two malformed shells, supernumerary marginals occur 

 only in the regions anterior to the normal position of M 3, and pos- 

 terior to that of M 10. This means that none occur except anterior or 

 posterior to the region of the doraal ribs. The exceptions are l^os. 

 145 and 248 (see Figs. 37 and 40, PI. IX, and ''Remarks" in 

 tables). Anterior supernumerary scutes were found in ISTos. 126 

 and 131 (Figs. 13 and 9). In each of these the first two marginals 

 (R and L in Xo. 126, R in Xo. 131), taken together, are about 

 equivalent to a normal first marginal. In Xo. 210 (Figs. 5 and 17) 

 the first right marginal was partially divided. 



Fig. L. 



Fig. K. Fig. M. 



Fig. K. Plastron of No. 132, showing anomalous soute on right side pos- 

 teriorly. Fig. L. Plastron of No. 233, supernumerary scute on left side. 

 Fig. M. Plastron of No. 88, left femoral and abdominal continuous mesially. 



Abnormalities are more common in the posterior region, addi- 

 tional marginals being observed on the left side in Xo. 235, on the 

 right in Xos. 88 (Fig. 12), 129, 151 (Fig. 7), 183 (Fig. 33) ; on 

 both sides in Xos. 35, 36, 37, 38, 108, 162, 178 (Fig. 30), 196 

 (Fig. 42), 198 (Fig. 45), 209 (Fig. 32), and 228 (Fig. 22); cf. 

 also Table V, Xos. 250 (R), 252 (R), 255 (L) and 256 (L) and 

 fieures. 



