578 E. C. CASE 



1. There have repeatedly been suggestions that reptiles occur in 

 beds below the Permian. Two examples suffice: 



As cited above, Cope identified a reptile in the beds of Linton, 

 Ohio. Following is a quotation from a letter written to the author 

 by the late Dr. Baur, dated June 20, 1897: 



I have found out that Hylonomus Dawson, and Dendrerpeton Owen, and 

 Petrohates Credner, are reptiles and not Stegocephalians. All these forms are 

 Carboniferous with the exception of Hylonomous, which is also found in the 

 Permian, and Petrohates, which belongs to the Permian alone. The vertebrae 

 are elongate and biconcave, chevrons intercentral, ribs two-headed, long, slender, 

 and bent. Teeth smooth, with large pulpa. Two sacral vertebrae, the second 

 with small sacral rib. No cleithrum. Interclavicle T-shaped, clavicle slender. 

 Ribs of caudal vertebrae bent backward. These forms are directly ancestral to 

 the Paleohateriidae. Microsauria Dawson is the proper name for them. This 

 fact, of course, makes the Microsauria the oldest reptiles, from which the Paleo- 

 hateriidae and the Rhyncocephalia are directly developed. 



The position taken in this letter was defended in the Anatomischer 

 Anzeiger, Bd. IV, pp. 146-51. 



2. The difficulty in distinguishing between the primitive reptiUa 

 and the amphibia has steadily increased by the discovery of inter- 

 mediate forms, so that it is practically impossible to draw a line 

 between the two today. The presence of a distinct parasphenoid 

 bone distinguishes the amphibia, and in the Texas beds the presence 

 of an entepicondylar foramen in the humerus distinguishes the 

 reptiles, but this cannot, perhaps, be depended on as a general 

 character of value. 



We now proceed to the consideration of smaller groups. 



Poliosauridae. — These may be related to the Proterosauridae 

 rather more closely than to the Pelycosauria with which they have 

 been described. Proterosaurus and Paleohatteria are typical mem- 

 bers of the Proterosauria from the Permian. 



Clepsydropidae. — No forms of this family occur in the Permian 

 of Europe. Ctenosaurus, an aberrant, related form, is from the 

 Bunter Sandstein and Anomosaurus, a doubtfully related form, is from 

 the Muschelkalk. 



Naosauridae. — A single species of this genus has been found in 

 the Permian of Bohemia. 



Pariotichidae. — No forms are known outside of the Texas beds. 



