BROILIELLUS, A NEW GENUS OF AMPHIBIANS 55 



Measurements 



684 68s 



Length of skull in midline 92 80 



Width posteriorly 85 74 



Anteroposterior diameter of orbits 24 20 



Interorbital width 27 25 



Length of carapace 120 100 



Greatest width of carapace 43 36 



Length of humerus 46 



Length of femur ' 54 



Length of tibia 35 



Length of median metatarsal 12 



The present genus is the fifth that has been described of the 

 pecuHar "batrachian armadillos" from the Permocarboniferous of 

 Texas and New Mexico, namely: Dissorophus Cope, Cacops 

 Williston, Aspidosaurus Broili, Algeinosaurus Case, and Broiliellus 

 Williston. The first two of these genera may at once be differenti- 

 ated by the completely closed otic notch; Aspidosaurus and 

 Broiliellus have the otic notch open behind; in Algeinosaurus the 

 skull is unknown. Aspidosaurus has typically a single dorsal 

 shield for each vertebra, firmly co-ossified to the expanded spine of 

 the vertebra, the shields are roof-shaped and narrow transversely. 

 Algeinosaurus has imbricated shields like those of Aspidosaurus, 

 narrow and shallowly V-shaped, but free from the broadly expanded 

 neural spines. It is possible that this freedom of the shields is due 

 to age, for I am convinced that the shields in all these forms are of 

 dermal origin. Until the skull of Algeinosaurus is discovered its 

 precise relations to the other genera cannot be determined. I am 

 convinced that it is nearly related to Aspidosaurus, but believe that 

 it is a distinct genus. It will at once be distinguished from the 

 present genus by the narrow, shallowly V-shaped, imbricated shields. 



Aspidosaurus glascocki Case can only be provisionally located 

 in this group. Its dorsal shields seem to be real expansions of 

 the spines, meeting each other closely, but not imbricated. Nor 

 can A. crucifer and A. apicalis be located here. I am confident 

 that all these forms belong in an entirely distinct group, possibly 

 the Zatrachydidae. 



That all the forms discussed above show a genetic relationship 

 there can be no doubt. Just what value the differential characters 

 present, however, is a question. If we give to Dissorophus and 



