"ABNORMALITIES" IN CHELONIA. 109 



believe, represent centers of dermal ossification and hence the 

 location of scutes that formerly occupied the position now occu- 

 pied by the spots. Evidences that serve to increase the proba- 

 bility of this conclusion may be adduced : 



1. Whenever supernumerary scutes recur each has at its 

 growth center an ocellatecl spot. 



2. These supernumerary scutes come in at places where normal 

 specimens have definitely placed secondary ocellated spots. 



3. There are never any secondary ocellated markings on the 

 marginal scutes, which agrees with our idea that the marginal 

 rows contain nearly their original number of scutes and hence we 

 would not expect to see traces of lost scutes in these rows. 



4. The light bands that form the reticulated pattern of adult 

 Graptemys have often the exact shapes of existing dermal plates. 

 This is particularly the case in the procaudal region. 



5. Considering the light bands as original scute boundaries, 

 we can count ten costal scute areas in Grapteinys or TracJiemys. 



6. On the neural scutes of Graptemys there are several much 

 smaller ocellated spots that lie near the outer edges of the scute. 

 These spots, I believe, are the vestiges of the small scutes that I 

 have earlier designated as neuro-costals, and that were the earliest 

 rows of scutes to be crowded out (Fig. 57). Four or more 

 well-developed spots occur close to the marginals on the costals 

 and occupy positions similar to the supramarginal scutes of 

 Macroclielys tcmmincki. 



At the angles made by adjacent neurals and costals occur 

 ocellated spots that have the appearance of having been squeezed 

 out between two scutes. These I believe to be the vestiges of 

 the lost neurals and costals (see Fig. 57). When the lost scutes 

 recur they have these spots at their growth centers. 



In the bridge region of Graptemys and Clirysemys a confused 

 series of dark colorations appears that seems to have no reference 

 to any existing structures. But when the inframarginals recur, 

 we find that these apparently meaningless markings fall into place 

 as the spots of this lost row of scutes. 



On the plastron scutes we find in most species a spot of pig- 

 ment for each member, but confusing secondary complexity 

 often obscures the real pattern. In Graplemys some specimens 



