270 PROCEEDINGS OF THE NATIONAL MUSEUM vol. los 



one, and the perpendicular of maximum depth (20.9 mm.) is situated 

 far posteriorly in the vertical plane of the dorsal and ventral apical 

 angles. 



The nucleus is a concentrated locus on the longitudinal axis of the 

 element, somewhat basal of the middle length of the scale. Surround- 

 ing this area in concentric fashion, relatively fine circuli (about 34 

 in 1 mm.) cover the dorsal, ventral, and basal quadrants of the external 

 surface. No basal radii are evidenced, but suggestive of such struc- 

 tures are a series of sinuous folds in the courses of the circuli, arranged 

 in an anteroposterior line across the median basal field. The circuli 

 terminate, posterodorsally, along a diagonal extending from the nu- 

 cleus to the middle point of the dorsal border and, posteroventrally, 

 along a more acutely oblique diagonal extending from the nucleus to 

 a point near the ventral apical corner of the scale. The apical quad- 

 rant is, thus, a triangular field with a nuclear angle of approximately 

 120°. The preserved portion of this part is ornamented with short 

 vermiculate markings which in the center of the field are directed 

 more or less longitudinally and on either side of this median area in 

 zones adjacent to the apical diagonals, vertically. Peripherally the 

 anterior terminations of generally longitudinal apical radii, spaced 

 4.5 to 5 in 1 mm., may be observed. From the comparisons discussed 

 below, it seems feasible to postulate the passage of these radii posteri- 

 orly across a missing marginal and hyaline zone to end in notches along 

 the dentate apical margin of the scale. 



The scale of Helmintholepis vermiculatus cannot be distinguished 

 from anterior flank scales of the upper Cretaceous Pierre shale fishes 

 Pelycorajpis herycinus Cope (1877) and Paleodupea dakotaensis 

 Dante (1942). From well-preserved specimens in the U. S. National 

 Museum, the skulls, as w^ell as the scales of the latter two genera, are 

 identical. It must be concluded, therefore, that Helmintholepis 

 vermiculatus and Paleodupea dakotaensis are synonyms of Pelycorapis 

 herycinus. Unfortunately, the generic term Pelycorapis does not 

 appear available for the herycinus species. Examination was re- 

 cently made in the American Museum of Natural History of the 

 genotypic specimen, Pelycorapis varius, defined by Cope (1874) on 

 the basis of a fragmentary fish from an undetermined horizon in the 

 "Benton" of Kansas. There can be little doubt of at least close 

 relationship, if not even conspecific identity, between P. varius and 

 the North American elopid fish Thrissopater intestinalis Moodie (1911). 



Woodward (1901, pp. 353, 354, 616) early advocated affinity, at 

 least at the family level, between the two species assigned to the 

 generic name Pelycorajpis (Cope, 1874, 1877), Syllaemus (Cope, 1875), 

 Apsopelix (Cope, 1871), and Leptichthys (Stewart, 1899). Apsopelix 



