PHYLOGENY OF SHELL OF TESTUDINATA 431 



of those scute areas and a part of that of the humerals appear 

 to have been covered by epithecal bones; if so, the latter have 

 disappeared. No bones or surfaces worthy of note appear at 

 the centers of growth of the gulars and the intergular. On the 

 plastron of no. 5911 no epithecal bones corresponding to those 

 mentioned are found, but plain traces of most of them are pres- 

 ent. They appear to have been thinner and usually to have 

 been absorbed. Nearly the whole free edge of the epiplastra 

 within the intergular scute area of the specimen in the National 

 Museum is occupied by two or three rough surfaces to which 

 were probably attached epithecal plates. 



Some months after the preceding paragraph had been written, 

 Dr. L. Stejneger found in his collection nearly all of the horny 

 scutes which had been removed from the shell of the mounted 

 specimen, no. 29545, above mentioned. These confirm the 

 writer's conjecture that the bones interesting us had been lost 

 from the skeleton in the course of preparation. Three verte- 

 bral scutes are preserved. On the inner surface of the first one, 

 at the point where the bone is to be looked for, there is a patch 

 of tissue 10 mm. long and 3 mm. wide; but, when it is thoroughly 

 moistened and then treated with hydrochloric acid, no reaction is 

 seen. The bone salts had probably been absorbed. The second 

 and third vertebral scutes are not preserved. On the fourth 

 there is a very distinct bone 14 mm. long and about 10 mm. wide. 

 Above, it is partly exposed by abrasion of the horny scute. On 

 the fifth scute there is distinct bone forming a patch 27 mm. 

 long and 8 mm. wide. It is partly exposed on the upper surface. 

 All of the costal scutes are preserved except the left second. Each 

 of the first costal scutes bears on the under surface a large and 

 thick patch of bone. That on the left side is 21 mm. long and 

 13 mm. wide. The bone of the right side is partially exposed 

 above; that of the left side is not. As stated above, the plates 

 of bone belonging under the second costal scutes remain on the 

 mounted skeleton. The left third costal scute retains its plate 

 of bone, 21 mm. long and 7 mm. wide. When a piece of it was 

 removed and put in acid abundant gas was liberated. The scute 

 of the right side also has its bone. Neither this nor that of the 



