PROCEEDINGS OF THE UNITED STATES NATIONAL MUSEUM 



SMITHSONIAN INSTITUTION 



U. S. NATIONAL MUSEUM 



VoL 108 Wa.hlngton : 1958 No. 3401 



THREE NORTH AMERICAN CRETACEOUS FISHES 



By David H. Dunkle 



I. Remarks on Hdmintholepis vermiculatus Cockerell 



Plate 1 



The North American Cretaceous fish Helmintholepis vermiculatus 

 Cockerell (1919) is based on a single disassociated scale (USNM 8677). 

 The specimen was collected in 1914 by T. E. Willard, of the U. S. 

 Geological Sm^ey, 1}^ miles northeast of Milliken, sec. 13, T. 5 N., 

 R. 67 W., Weld Count}-, Colo., in exposures of the Fox Hills sandstone 

 (Maestrichtian). 



The scale, presumably deriving from the left flank of a fish, is com- 

 paratively large and, although composed of successive fine lamellae, 

 is of remarkable over-all thinness. The major portion of the apical 

 margin is missing. The outline of that part impressed in the matrix, 

 however, indicates a roughly 5-sided form for the scale. Of these 

 edges the broadly rounded apical margin has the greatest length. 

 The dorsal and ventral borders converge slighth' toward each other, 

 anteriorly, to distinct but obtuse basal angles. The basal margin is 

 divided into upper and lower segments b}^ a low, forwardly convex, 

 median lobe. The greatest length of the scale (21.4 mm.) passes along 

 a longitudinal axis a little nearer the dorsal border than to the ventral 



468792— 5& 269 



