50 Kobert E. Coker. 



The length is the full length of the carapace measured over the 

 dorsal curvature and expressed in millimeters. The day of the 

 embryo is indicated, when the embryo was taken from the egg alive, 

 but the stage of development is perhaps best inferred from the 

 carapace length, since the length of the incubation periods varies 

 within wide limits (73, or less, to 90 days, or more). It was longer 

 for eggs in the incubator than for those in the ground. "B" in 

 the "day" column, indicates that the specimen was new-born, 



2. Obsekvations on Diversity. 



The carapace differs from that of Malaclermnys in shape — it has 

 a more aquatic form. It is broad in the anterior region, where the 

 long stout swimming flippers are, and tapers to a comparatively 

 narrow but rounded posterior end. The margin is indented over the 

 anterior flippers, and sometimes slightly so over the posterior. As 

 if in adaptation to the shape, with broad anterior end, the nuchal 

 is very wide and the costal series terminates anteriorly in a small 

 scute not represented in Malaclemmys, and others. There is often 

 one more marginal in this region than is found in land and marsh 

 turtles. 



In Table VI are presented the observations on 34 embryos from 

 the nest transplanted at the laboratory in 1903. Besides the fact 

 of removal in the first instance, the conditions of development 

 were othei-wise abnormal. Only a small proportion developed suc- 

 cessfully and most were removed from the nest during the period 

 of incubation. Only one (ISTo. 32) actually hatched. 



Twelve of the 3-1: are abnormal in number or arrangement of 

 scutes or in showing partial division of a scute. The abnormality 

 frequently manifests itself in an asymmetrical plan of neural and 

 costal scutes (Nos. 1, 23, 24, 26, 30, 31). In other cases the costal 

 series of the two sides are unsymmetrical in number, without effect 

 on the symmetry of the general plan of series (Kos. 6, 10, 21, 25). 

 The proportions of these embryos with the several marginal plans 

 referred to on p. 49, above, are interestingly uniform. Of the 29 

 specimens, in which the marginals could be counted with certainty, 

 ten have the 13-13 plan, ten the 12-12 plan, and nine either 13-12 or 



