PHYLOGENY OF SHELL OF TESTUDINATA 433 



left of the center of the figure is a little bony plate marked by a 

 conspicuous border. This was taken from its resting place and 

 returned. Near it, on the right hand, is a larger patch, slightly 

 lower than the general surface and in which there was once a 

 little five- or six-sided plate. Near the upper left-hand corner is 

 a pretty large irregular .and rather indistinct surface which rises 

 onto the scute area in front of it. The appearance indicates 

 that the plate of bone which occupied it had long been absorbed. 

 On its right again there is a little plate which has become pretty 

 thoroughly coossified with the bone around it. At the lower 

 end of the figure are two plates whose outlines are rather indistinct. 

 A good many similar areas are found scattered here and there 

 over the surface of the carapace of no. 6596. Also on the cara- 

 pace 5911 a few such areas are found. On the disarticulated 

 carapace 7167 manj^ shallow pits are found which appear to have 

 been filled by little plates of bone; but these may have come 

 away with the horny scutes at the time of maceration. On this 

 shell they appear to be clustered especially around the bosses 

 of bone belonging to the various scute areas, but they are found 

 also elsewhere. They do not appear to be due to any abnormal 

 condition of the bone, and they were certainl}^ buried under the 

 horny scutes. 



Many of these small plates which are distributed without 

 order are found on the flat part of all of the three plastra from 

 the American Museum. On no. 7167 (fig. 9) a number of these 

 are seen fixed in their pits. In other cases they are gone, ab- 

 sorbed or lost in maceration. On the plastron of no. 6596 have 

 been many such plates. A few remain, but of others only their 

 impressions are left. An oval one is 10 mm. long; another appar- 

 ently occupied by a single plate is still larger. On the plastron 

 of no. 5911 are seen shallow depressions in which had rested bony 

 plates, some of them of considerable size. 



After the greater part of this paper had been written, still 

 another specimen of Chelys was put into the writer's hands for 

 examination. This had been in the Zoological Park for some 

 months. It had never been known to take any food, and it 

 probably died of starvation. Since a hole is found bored through 



