6 THE HISTORY OF THE PELYCOSAURIA, WITH 



astragalus, considered first as a coracoid bone, and some phalanges, which were provi- 

 sionally referred to the same genus. The vertebras are deeply biconcave, and notochordal. 

 There are no processes on the centra, but a small capitular, articular face is present 

 on the anterior articular edge of two of the dorsals. The dorsal vertebrae have the sides 

 somewhat contracted ; in one specimen the inferior face rounded, in another it is longi- 

 tudinally acute. The diapophysis does not project far beyond the base of the neural 

 arch, and is compressed. The caudals are elongate. Then follow remarks about the 

 ribs, astragalus and phalanges. That these remains belonged to a small animal is indi- 

 cated by the size of the vertebrae : 



M. M. 



Length of centrum of sharp keeled dorsal 0.014 of rounded dorsal 0.012 



Depth behind 0.012 0.011 



Width behind 0.012 0.0105. 



Cope says of Clepsydrops : " This genus is more typically Rhynchocephalian than Cri- 

 cotus," not knowing at that time that Cricotus is one of the Stegocephali (Labyrin- 

 thodonta). 



The next communication was made by Cope 2 in 1877. Clepsydrops is now placed 

 definitely among the Rhynchocephalia. Clepsydrops collettii Cope is said to be the 

 most abundant land vertebrate of the formation, being represented in all the collections, 

 sometimes by portions of individuals of double the size of the type. There is a single 

 occipital condyle. Two new species of Clepsydrops are described, C. vinslovii and C. 

 pedunculatus. 



C. vinslovii Cope is based on a third cervical vertebrae, and probably represented by 

 other vertebrae. C. pedunculatus Cope is established on a third cervical and another, 

 apparently dorsal one. This species is said to be characterized by the stronger dia- 

 pophyses. 



Teeth are described, Species No. 4, p. 56, and are referred to Clepsydrops collettii. 

 The horizon from which the fossils came is now considered as Permian, and is named the 

 Clepsydrops shale. 



In the same year the discovery of Permian Reptiles in Texas was announced by Cope, 3 

 and other remains from Illinois are described. Lysorophus tricarinatus Cope is named 

 and described. " Vertebrae amphicoelian, perforated by the foramen chordae dorsalis. 

 Neural arch freely articulated to the centrum. Floor of neural canal deeply excavated. 

 No processes nor costal articulations on the centrum, which is excavated by 

 longitudinal fossae. Centrum not shortened." From near Danville, Illinois. Based on 

 two. centra and a portion of a third. Another new genus and species is based on teeth : 

 Archmobelus vellicatus, " Species No. 4," Cope, Proc. Amer. Philos. Soc, 1877, p. 192. 



