56 S. W. WILLISTON 



Aspidosaurus family rank it will be necessary to erect a larger 

 group to comprise them all. I would rather place them all in the 

 family Dissorophidae, in two subfamilies, the Dissorophinae and 

 Aspidosaurinae. 



Family Dissorophidae 



Temnospondyl amphibians of small size, provided with dorsal osseous 

 shields. Skull broad, depressed, more or less rugose, without mucous canals. 

 Lacrimal entering orbit. Probably orbital ossifications in all. Otic notch 

 greatly developed, extending far toward the orbit. Palate with slender para- 

 sphenoid; in front at least covered with chagrin-like teeth; two enlarged 

 teeth only. Occipital condyles separated. Cleithrum large; clavicles and 

 interclavicle small, not sculptured. Sacrum with two vertebrae (in all ?) ; 

 pelvis fully ossified, platelike. Femur with high, thin adductor crest. Feet 

 fully ossified, short and rather broad. No ventral armature. 

 Subfamily Dissorophinae 



Otic notch closed posteriorly by the union of tabulare with quadrate 

 below. Each vertebra with two dorsal shields, the under one either an expan- 

 sion of the spine or a dermal ossification and smooth, the intercalated external 

 shields sculptured. 

 Genus Dissorophus 



Shields covering nearly the whole of the dorsum, the first one of large size. 

 Genus Cacops 



Shields narrow, the first one small. 

 Subfamily Aspidosaurinae 



Each vertebra covered by a single, sculptured shield. Otic notch open 

 behind. Ribs with uncinate process. 

 Genus Aspidosaurus 



Spines greatly expanded above, with shields not much wider than vertebrae, 

 and imbricated; more or less V-shaped. Orbits more posterior. 

 Genus Algeinosaurus 



Like Aspidosaurus but the shields not coossified with spine. 

 Genus Broiliellus 



Shields much broader than the vertebrae, not imbricated and not V-shaped; 

 free from slender neural spines; skull spinose. 



Dissorophus muUicinctus Cope. Texas. 



Cacops aspidophorus Williston. Texas. 



Aspidosaurus chiton Broili. Texas. 



Aspidosaurus novomexicanus Williston. New Mexico. 



Algeinosaurus aphthitos Case. Texas. 



Broiliellus texensis Williston. Texas. 



Broiliellus peltatus Williston. Texas. 



