I903-] 



Hay, North American Cretaceous Fishes. 



79 



Fig. 63 represents the lower jaw seen from the outside. It 

 is ever5'-where ornamented with radiating ridges and grooves. 

 In front are three deep notches, as in many species of the 



Fig. 63. Enchodus scevus Hay. No. iq8. X 3. Type. Lower jaw, outer 

 view, ang., angular; art.^ articular; den., dentary. 



genus. Fig. 64 shows the lower jaw from the lingual side, 

 together with the ectopterygoid and quadrate. The two last- 

 mentioned bones are somewhat displaced. Attention is 

 called to the great raptorial tooth on the anterior end of the 



(*L l^-gs-?vf ec^ 



Fig. 64. Enchodus scpvus Hay. No. ig8. X 3. Type. Lower jaw, 

 quadrate, and ectopterygoid ; inner view, ang., angular ; art., articular ; den., 

 dentary ; ec. pi., ectopterygoid ; gu., quadrate. 



ectopterygoid. It is about 30 mm. long. The upper border 

 of the ectopterygoid is excavated in front and received the 

 lower border of the palatine. 



One preoperculum is present (Fig. 65). It appears to me 

 to belong to the left side. It is very narrow above, but 

 broadens somewhat below. The exterior surface is convex 

 transversely and has ridges and grooves running lengthwise. 

 A conical process from its front border fits into a groove in 

 the hinder border of the quadrate. On the inner face of the 

 preoperculum there is a deep channel running nearly the 

 full length and opening forward. What I regard as the left 

 interoperculum is shown in Fig. 65, i. op. A portion of its 



