72 



CATALOG OP FOSSIL FISHES IN THE MUSEUM 



a condition being known in only a few Arthrodira, and in none of 

 them being better shown. The form with which the element can 

 best be compared as regards this feature is Dinichthys herzeri, in which 

 the postero-superognathal has a row of ornamental denticles extend- 

 ing diagonally upward across the outer face very much as in the speci- 

 men here described. ^^ This species is, however, of huge size as com- 



FiG. 23. Stenognath'.is denticulatus, n. sp. Right Postero-Superognathal. 



Type, X 2 



a, outer view showing the oblique row of denticles. Most of this side of the 

 element is covered with matrix, indicated by the stippling, b, inner view. E 

 2386. 



pared with the present specimen, and also, the postero-superognathal 

 is not so elongated. 



From its homolog in Stenognathus mixeri described on p. 75, it is 

 distinguished by its relatively greater elongation and by tapering 

 more to a point in its distal half. 



32 For a figure of the postero-superognathal in Dinichthys herzeri see Hussakof, L.: Studies on the 

 Arthrodira. Mem. Amer. Mus. Nat. Hist., ix, pi. xiii, fig. 3, 1906. 



