348 



BAUR. 



[Vol. IV. 



In another direction, possibly from the Platysternidag, devel- 

 oped the form of pelvis seen in the Emydidae and Testudinidae. 

 Among the more generalized forms of Emydidae, like Malaco- 



FlG. 4. — Cinosternum pennsylvanicum, var. 



E, Epigastroid. 

 H, Hypogastroid. 



clemmys, we find that entopubes and entoischia just begin to 

 touch each other. In the young animals there is a continuous 

 gastroid cartilage, only in older animals entopubes meet, and so 

 do the entoischia. In this stage we find a cartilaginous epigas- 

 troid, mesogastroid, and hypogastroid. The same condition I 

 have observed in CJiryseniys picta. In the next stage entopubes 

 and entoischia unite, but the cartilaginous mesogastroid is still 

 present (Trachemys, Pseudemys, Terrapene, Clemmys, Geoe- 

 myda). In Emys the mesogastroid becomes ossified, and forms 

 a slender element, pointed behind, and placed on the ventral 

 side on the anterior portion of the united entoischia. Cyclemys 

 is very near this stage. The epigastroid is always present in 



Fig. 5. — Malacoclemmys geographica, 

 Les. 



E, Epigastroid. 

 M, Mesogastroid. 

 H, Hypogastroid. 



middle-aged specimens. It may calcify or ossify, or may become 

 absorbed by the entopubes. The hypogastroid I never found 

 ossified ; it is either cartilaginous, but very small, or absorbed 



