64 



AMPHIBIA AND PISCES OF THE PERMIAN OF NORTH AMERICA 



The large, round orbits mostly in the posterior half. The nares large, nearly- 

 round, widely separated from each other and located on the outer edges of 

 the snout. Lyra absent. Otic slit present. The surface of the skull rough; 

 the posterior prolongation of the supraoccipltal without ornamentation. 

 The small teeth of similar size, conical, slender, and closely set together, 



"The lower surface of the skull shows trace of a thick plaster of chagrin 

 teeth. 



"Vertebrae rhachitomous. Neural spines expanded distally; with an 

 arrangement like roofing tile, the surface roughly sculptured. The spines 

 overlapping each other to form a sort of carapace." 



Revised description of the genus: 



1. Skull elongate triangular, with broadly rounded nose. Resem- 



bling Trimerorhachis. 



2. Apices of neural spines expanded into overlapping rugose plates. 



3. Intercentra without lateral processes for the head of the rib. 



Revised description of the species: 



1. Expanded processes of neural spines narrow: the two sides 



slanting upwards to meet in a narrow ridge. 



2. The intercentra with distinct keel and the lateral processes small. 



Fig. 14.^ — A. glascocki. No. 4864 Am. Mus. 



A. Superior view, showing character of top of 



neural spines of Jjrsal veriebrje. 



B. Lateral view. 



C. The same, inferior view, showing intercentra 



with prominent lateral processes for ribs. 



Aspidosaurus glascocki Case. 

 Bull. Am. Mus. Nat. Hist., vol. xxviii, 1901, p. 179. 



Type: A portion of the vertebral column with fragments of the skull. 

 No. 4864 Am. Mus. Nat. Hist. From Texas. 



Original description: "The new species, A. glascocki, differs from A. 

 chiton Broili, in having the expanded apices of the neural spines much larger 

 and marked with a coarser sculpture. The apices of the spines touch but 

 do not overlap. The intercentra have prominent processes on the sides for 

 the heads of the ribs. In A. chiton there are facets, a little more prominent 

 than in Eryops and Trimerorhachis, while in A. glascocki they are extended 



