CRETACEOUS FISHES — DUNKLE 275 



The original description of Cyclolepis stenodinus now may be ex- 

 panded. A relatively thin scale of moderate size (measurements, in 

 millimeters: 12.4 long by 9.7 deep). In outline, subcircular with 

 broadly rounded and confluent dorsal, apical, and ventral margins; 

 obtuse but distinct basal angles; and a centrally lobed basal edge. 

 Perpendicular of maximum depth adjacent to the basal angles and 

 thus situated far anteriorly. Nucleus a concentrated focus both in- 

 ternally and externally, slightly apicad of central. No basal or apical 

 radii, but suggestive of the former are several (three or more) indis- 

 tinct folds or undulations in the courses of the circuli across the 

 central part of the basal field, arranged in lines convergent posteriorly 

 toward the nucleus. Circuli on anterior inserted portion of scale 

 coarse (18 in 1 mm. centrally and 12 in 1 mm. peripherally above and 

 below, and in their posterior zone of termination along the apical 

 diagonals) ; essentially vertical in arrangement althougli slightly curved 

 in an anterior du-ection around the nucleus and bent posteriorly both 

 along the ventral basal diagonal and in an upper peripheral zone so 

 that the dorsal ends of the lines intersect the scale margin at more 

 acute angles than do the ventral ends. Interspaces between the more 

 widely separated circuli of the dorsal and ventral quadrants marked 

 by short, fine, parallel striae (10 to 12 in 0.1 mm.), directed at acute 

 angles to the circuli and generally perpendicular to the anteroposterior 

 axis of the scale. Apical field triangular with a nuclear angle of about 

 101°; ornamented with fine circuli (34-36 in 1 mm.) arranged in 

 parallel but slightly undulating crescentic courses to meet the termina- 

 tions of the basal circuli along the apical diagonals in angles of ap- 

 proximately 90°, Internal surface of scale distinctly marked by 

 sparsely tuberculous and concentric annular growth rings which are 

 in places so closely set they resemble concentric cu-culi. 



No materials of the genotypic Cyclolepis agassizi are available for 

 comparison. Notwithstanding, the characteristics of the scale of 

 Cyclolepis stenodinus are not those either commonly or easily asso- 

 ciated with the scales of salmonoid fishes. Rather, scales of its type 

 with essentially vertical circuli which are coarser in the basal portion 

 than in the apical one and with nearly central nuclei are better recog- 

 nized as pertaining to the Synentognathi, Scombrcidea and Caran- 

 goidea. During search among these latter groups for more closely 

 comparable materials, striking and fundamental similarities were ob- 

 served between C. stenodinus and Hemilampronites hesperius Cockerell 

 (1919). In fact, only minor differences of shape, absolute size, and 

 slight details of sculpture exist between the two species and these 

 are well within the range of variation to be expected between scales 

 from different parts of the body of one fish. Interestingly also, the 



