Figure 4. — Diagrams showing general shapes of claspers and clasper siphons in adult male eat sharks : A, 

 Scyliorltinus torrei and B, Galeus arae, both from the Florida Straits; C, Schroederichthys tnacufatus 

 from the western Caribbean ; and D, Apristurus riveri from the southwestern Caribbean. Each drawn 

 to scale but scales are unequal. 



structures in some scyliorhinids in detail (Leigh- 

 Sharpe 1920, 1922, 1924, 1926a, and 1926b). In 

 practical application for taxonomic studies, how- 

 ever, fhere is some difficulty because of inadequate 

 series of specimens. Of the 15 western Atlantic 

 scyliorhinids treated here, for example, adult 

 male specimens were not available for 6 species. 



Diagrams outlining the genera] size and shape 

 of claspers in relation to the pelvic fins and outlin- 

 ing roughly the extent of the clasper siphons are 

 shown in figure 4 for representatives of four west- 

 ern Atlantic genera. No important differences in 

 gross examination were noted among adult males 

 of the two species of western Atlantic Galeus. 

 Supplementary examination of a few adult male 

 Galeus from the eastern Atlantic and from the 

 Pacific failed to reveal substantial differences in 

 clasper structures within the genus excepting the 

 presence of hooks on specimens of western 



Atlantic' species examined and the absence of these 

 on the only eastern Atlantic adult male available. 

 The available material is insufficient to show 

 whether clasper structures of western Atlantic 

 scyliorhinids are useful in the diagnosis of species, 

 but from a necessarily cursory review it appears 

 that they might be quite useful as generic 

 characters. 



Hooks were present on claspers of the species 

 of Galeus but were absent on Apristurus and 

 Schroederichthys and from the claspers of west- 

 ern Atlantic tScyliorhhius examined. Hooks were 

 not found on a clasper of one Galeus melastoirms 

 from the eastern Atlantic. 



The denticles on the surfaces of claspers in all of 

 the specimens examined have their points directed 

 forward toward the base of the clasper. The re- 

 versal of direction of the denticles is noted as oc- 

 curring in Scyliorhinus stellaris (=ScyUium 



f,NS 



U.S. FISH AND WILDLIFE SERVICE 



