as large as first dorsal ; dorsal fin bases separated 

 by a distance about equal to length of anal base; 

 second dorsal similar in shape to first dorsal, its 

 origin posterior to middle of base of anal, its pos- 

 terior tip separated from origin of caudal crest 

 by a distance equal to one-half horizontal diameter 

 of orbit; pelvic fins large and long, united and 

 adnate to body for a short, distance posterior to 

 anus, their posterior tips pointed; anal fin long, 

 its base 2y 2 times base of first dorsal, its height 

 about equal to height of second dorsal; upper 

 caudal with crest of modified denticles (see fig. 

 21B), caudal fin slightly less than one-third total 

 length; lower caudal fin about same height as anal, 

 its margin rounded without forming a pointed 

 lobe, a notch near the tip. 



Denticles over dorsolateral surfaces small, three 

 pointed, the central point much the longest, similar 

 to denticles of G. arae (see fig. 7) . 



Teeth relatively small, multicusped, largest 

 three or five cusped with central cusp much the 

 longest, similar in shape in upper and lower jaws, 

 several series functional; upper teeth in 31 + 31 

 rows; lower teeth in oblique series, not readily 

 counted by row. 



Notes. — Galeus cadenati, so far as known, is 

 found only in the southwestern Caribbean off the 

 coast of Panama. Although this is quite near the 

 range of Galeus arae, which occurs off the coast 

 of Nicaragua, the collections seen show no over- 

 lapping. 



Eastward and along the Caribbean or Atlantic 

 coasts of Columbia, Venezuela, the Guianas, and 

 northern Brazil, specimens of Galeus have not 

 been reported although collections from these areas 

 have produced many small sharks of other genera 

 in depths at which Galeus would be expected to 

 occur. 



Genus Apristurus Garman, 1913 



Type species Scylliorhinus indicus Brauer, 1906, by 

 original designation. 



The genus Apristurus as understood here 

 (Pentanehus profundicollis Smith and Radcliffe 

 is excluded) contains about 16 species. Four west- 

 ern Atlantic species are recognized. Members of 

 the genus are small sharks, for the most part less 

 than a meter long, with broad and flattened heads 

 which are sometimes described as shovel-shaped. 

 All of the known species are rather uniform black 

 or dark brown in life. Lighter colors on some 



museum specimens (Apristurus profundorum) are 

 thought to be due to handling accidents or to ef- 

 fects of preservatives. 



Various sets of characters have been used in de- 

 scriptions of species of Apristurus, but most 

 authors have relied on morphometries to define 

 species. This has not been very satisfactory be- 

 cause some descriptions have had to rest on single 

 specimens and at best the series are small. Added 

 to this, specimens of Apristurus preserved in 

 alcohol quickly become wrinkled and fragile. 

 Measurements are difficult to make, and the body 

 proportions and fin positions in the series measured 

 appear to vary considerably within species. 



So far as known, all species inhabit deep water, 

 specimens for the most part being taken from 

 depths of more than 600 m. 



KEY TO WESTERN ATLANTIC APRISTURUS 



1A. Denticles over most dorsolateral areas narrow, 

 erect, not imbricate, their bases separated by dis- 

 tances greater than the diameter of a denticle base ; 

 a caudal crest of wide, imbricate denticles of about 

 uniform size, their tips not pointed upward, form- 

 ing a rather smooth surface, extending a short dis- 

 tance onto the lateral surface of the tail, the crest 

 denticles in sharp contrast (see fig. 23) to the very 

 sparsely scattered, narrow and erect denticles of 

 the lateral surface of the tail ; pelvic fins compara- 

 tively short, somewhat thickened, broadly ovate in 

 shape; anal fin relatively high, its anterior and 

 distal margins forming a continuous smooth 

 curve Apristurus profundorum 



IB. Denticles over most dorsolateral surfaces moderate- 

 ly broad, close together, imbricate or at least very 

 closely arranged with small spaces between bases; 

 denticles of upper margin of tail not differing great- 

 ly in shape, size or density of arrangement from 

 denticles of lateral surfaces of tail ; pelvic fins com- 

 paratively long, lanceolate; anal fin either high 

 or low but with its anterior margin and distal mar- 

 gin forming an angle, the two margins not rounded 

 as a continuous curve . 2A or 2B 



2A. Head comparatively narrow with narrow band of 

 prominent mucous pores of underside of snout ex- 

 tending medially from front of mouth nearly to tip 

 of snout in four or sometimes six longitudinal rows ; 

 tip of snout notably constricted at anterior end of 

 nostrils; teeth comparatively large and sexually 

 dimorphic Apristurus riveri 



2B. Head comparatively broad with a wide band of prom- 

 inent mucous pores of underside of snout extending 

 medially from front of mouth nearly to tip of snout 

 in eight or more longitudinal rows ; tip of snout not 

 notably narrowed at nostrils ; teeth comparatively 

 small with no sexual dimorphism 3A or 3B 



REVIEW OF WESTERN ATLANTIC CAT SHARKS 



611 



