THE PERMIAN FISHES OF NORTH AMERICA I73 



"Measurements. mm 



"Transverse diameter skull near posterior end of maxillary 200 



Length of parasphenoid 86 



Width of parasphenoid at occipital cotylus 25 



Width of parasphenoid at middle 16 



Diameters of anterior face of basihyal: 



Vertical II 



Transverse ' 27 



Width of basibranchial 9 



Length of (?) ceratohyal 80" 



(?) Genus PYRITOCEPHALUS Fritsch. 



Among the specimens collected by Professor Case in Texas there is 

 a small dermal bone (No. 7934 Am. Mus.) ornamented similarly to the 

 cranial bones of Pyritocephalus Fritsch as described and 

 figured by that author in his "Fauna der Gaskohle," 

 vol. Ill, p. 86, pi. 115. It is shown, natural size, in fig. 55. 

 The ornamentation consists of heavy raised lines more 

 or less concentric in arrangement. The single plate is, 

 of course, too fragmentary for specific description; but 

 it is interesting as evidence of the presence in the Texas 

 Permian of another of the forms occurring in the Permian 

 of Bohemia. Professor Fritsch regards Pyritocephalus Fig 55— Dermal bone of 



, , ^ . f. .,*>,, y . , ^ Pyritocephalus (?), No. 



as a typical member of the family raLceoniscidce. 7934 Am. Mus. Texas. 



Genus PLATYSOMUS Agassiz. 

 Poiss. Fos., n, Pt. i, 1835, pp. 6, 161. 



Revised description of genus: 



1. Trunk much deepened. 



2. Marginal teeth, small, styliform. 



3. Dorsal and anal fins much elongated, the anal somewhat shorter 



than the dorsal but terminating posteriorly opposite the end 

 of the dorsal; caudal heterocercal with the lower rays elon- 

 gated so as to make the tail appear equilobate; ventrals small 

 and nearer to anal than to pectorals. 



4. Fin-rays articulated, distally subdivided. 



5. Fulcra small, usually on all fins. 



6. Flank-scales much deepened; ornamented with very fine paral- 



lel lines; articulating by peg-and-socket joints; scales gradu- 

 ally decreasing in depth dorsalward, ventralward, and towards 

 the caudal. Ridge-scales present along dorsal and ventral 

 margins; those in front of dorsal and anal smallish, those 

 in front of upper lobe of caudal large. 



Platysomus palmaris Cope. (Text fig. 56 and plate 30, fig. 7.) 

 1891. Platysomus palmaris, Cope, Proc. U. S. Nat. Mus., xiv, p. 460, pi. xxxiii, fig. 10. 



Type: Numerous fragments, bearing scales, and portions of the pectoral 

 girdle. No. 7281 Am. Mus. Red Beds, Indian Territory. 



Referred specimen: An elongated nodule 3 by 9.5 cm., containing a 

 defective fish which exhibits flank scales, caudal fin, and portions of the 

 dorsal and anal. No. 7935 Am. Mus. Texas. (Fig. 56 a.) 



