254 University Geological Survey of Kansas. 



longitudinally, gently convex on the upper part. A single 

 denticle present, slender, flattened cylindrical, with an anterior 

 and posterior carina ; it arises below the base of the main cusp, 

 and is directed more outwards, its inner surface concave longi- 

 tudinally. Immediate base of crown of both main cusp and 

 denticle with short ridges. Base of tooth short, truncate (?) 

 below the main cusp, prolonged downward below the denticle. 

 Length of main cusp, 19 mm. ; width of same at base, 5 mm. ; 

 length of denticle, 5 mm. ; width of same at base, 2-J- mm. ; 

 height of tooth, 26 mm. ; width of base, 10 mm. 



A small tooth of the same form found with this has a total 

 length of 14 mm. The base is deeply emarginate below, with 

 two slender roots ; that below the denticle the longer. Mentor 

 beds, 4£ miles southwest of Marquette, Kan. 



U. S. Nat. Mus. No. 1979. 



PYCNODONTIDJE. 



The pycnodonts are a peculiar group of ganoid fishes, whose 

 remains have been found in the Jurassic, Cretaceous and Eo- 

 cene deposits of Europe, North America, Asia, and Australia. 

 They are all rather small fishes, very much flattened and oval 

 in shape, covered with rhomboidal scutes having close-lying 

 spines, which give a ribbed appearance. The united palatine 

 and vomer of the upper jaws are provided with five rows of 

 round or oval, smooth-pavement teeth; the premaxillary with 

 two or four chisel-like teeth. The dentaries below have a like 

 number of teeth, similar to those of the premaxillary, while on 

 the splenial there are three, four or five rows of pavement teeth 

 similar to those of the vomer. 



Cceloclus brownii. Plate XXIV, fig. 12. 



Ccelodt/.s brownii Cope, Journ. Acad. Nat. Sci. Phil., ix, p. 447, pi. xx, 

 f. 19; Williston, cf. cit. 28. 



A fragment of the left lower jaw, containing two rows of 

 teeth, the middle and the inner. There are four crowns pre- 

 served on the inner row, nearly corresponding in length with 



