178 KANSAS UNIVERSITY QUARTERLY. 



Sagenodus copeauus, n. sp. 



Dental plates of upper jaws elongate, the inner curve parabolic-like, 

 becoming greater posteriorly. Anteriorly the ridge bordering the 

 plate becomes very pronounced, and terminates in a prominent point. 

 The succeeding ridges become less and less prominent and less ob- 

 lique, the fifth running transversely, the last, or ninth, merely forming 

 a tubercle on the outer margin. The nine ridges include the borders 

 of the plate, there being eight dejDressions between them, the last 

 scarcely distinguishable, and short. The general surface of the crown 

 is concave and smooth, the ridges sharp, and terminating in tooth-like 

 points. The coronal surface is everywhere smooth, without denticles, 

 tubercles, or pittings. The palatine plate below the dental plate an- 

 teriorly on the inner side is gently concave. The border for union 

 with its mate is straight and very oblique, terminating about oppo- 

 site the third dental serration ; posteriorly the dentigerous plate is 

 strongly convex above, arching outward as far as the hind end of the 

 dental plate. Above this convexity the inner surface is gently concave, 

 and the plate is here very thin. On the upper border, beginning a 

 little way back of the symphseal border, there is a narrow sutural sur- 

 face for union with the para.sphenoid or basale. At the posterior ex- 

 tremity the broad end is beveled outward into a thin border, and is 

 cut off nearly transversly. Externally the surface is flattened and 

 very oblique above the margin of the dental plate. Back of this the 

 surface is more flattened vertically, with a narrow portion on the up- 

 per part turned inward. Where this surface turns inw^ard, there is an 

 elevation and roughening, as though for cartilaginous or bony union. 



The pterygopalatine plate, while shaped much as in Ceratodus, 

 difPers markedly in being less elongate posteriorly, more expanded 

 and nearly squarely truncate. The anterior ends of the dentigerous 

 l^lates evidently approach each other more closely than in Ceratodus, 

 the innermost ridge and its projecting tooth lying more closely to- 

 gether, with only a narrow interval between them. 



None of the bones found in the rock are in connection, or but very 

 few of them are. The determination of many must be very difficult 

 at present, since so little is known of the anatomy of allied forms. It 

 is very evident that the ossification of the skeleton is more extensive 

 than in Ceratodus, though many of the bones, especially the verte- 

 brjv, remained cartilaginous. So many of the shield bones of the 

 head are present that one will readily eliminate from them the bone 

 which seems certainly to be the parasphenoid or basale of Guenther. 

 It is diamond-shaped, with a moderately long posterior projection. 

 The surface that seems to be the upper one is smooth, gently concave 

 in the middle, with a median ridge beginning near the middle and be- 



