ZOOLOGICAL POSITION OF THE RED- 

 BELLIED SLIDER TERRAPIN. 



SuBKiNGDOM, Vertebrata. Division, Saiiropsida. Class, 

 Reptilia. Order, Chelonia. Family, Emydoidse. 

 Genus, Pseudemys. Species, rugosa. 



Characters of the Sauropsida.* 



1. Almost always an epidermic skeleton, in the form 

 of scales or feathers. 



2. The vertebral centra are ossified, but have no ter- 

 minal epiphyses. 



3. The skull has a completely ossified occipital seg- 

 ment and a large basi-sphenoid. There is no separate 

 para-sphenoid in the adult. The prootic is alwrays ossi- 

 fied, and either remains distinct from the opisthotic 

 and epiotic during life, or unites with them only after 

 they have anchylosed with adjacent bones. 



4. There is always a single convex occipital condyle, 

 into which the ossified ex-occipitals and basi-occipital 

 enter in various proportions. 



5. A mandible is always present, and each ramus 

 consists of an articular ossification and several mem- 

 brane-bones. The articular is connected with the rest 

 of the skull by an ossified quadrate. 



6. The apparent ankle-joint lies between the proxi- 

 mal and distal divisions of the tarsus. 



* The characters given are taken, with slight modification, from Huxley. 



I 



