CLEPSYDROPID^. 



105 



groups found in the Galesauridce. Vertebrae notochordal, with in- 

 tercentra, and frequently with an extraordinary development of the 

 neural spines (fig. 24); no zygosphenes, and the pre- and post- 

 zygapophyses widely separated from one another, with oblique 

 articular surfaces. Humerus typically with the shaft much con- 

 stricted, the distal expansion wider than the proximal, and the 

 proximal articular surface at right angles to the sides of the bone. 



Fig. 23. 



Stereorhachis dominans. — Palmar aspect of the left humerus, imperfect proxi- 

 mally ; from the Lower Permian of France. \. {After Gawky.) 



In the type genus Clepsy drops, Cope *, the three elements of the 

 pectoral girdle are coossified into a single bone 2 ; while in Dimetr- 

 odon 3 the pelvic bones form an innominate. 



The humerus of Stereorhadiis, Gaudry 4 (fig. 23), from the Upper 

 Permian of France, corresponds with the description of that of Clep- 

 sydropst 



1 Proc. Ac. Nat. Sci. Philad. 1875, p. 407. 



2 See Eep. Amer. Assoc, vol. xxxiii. pi. facing p. 481. 



3 See Proc. Amer. Phil. Soc. vol. xvii. pp. 513, 514 (1878). 



4 Les Euchainements du Monde Animal, etc. — Fossiles Primaires, p. 279 



(1883). 



