2 86 Memoir Sears Foundation for Marine Research 



is known of their habits. So far the genus is known only along the north and south 

 coasts of Cuba, in the northern part of the Gulf of Mexico off Pensacola, Florida, and 

 northward along the continental slope of the southeastern United States to the offing 

 of South Carolina, the most northerly record (for a specimen of B.plutonia) being 

 Lat. 32°43' N, Long. 77°2i' W. But it may prove that some short-nosed Skates from 

 other parts of the world that are now referred to Raja actually belong in this genus. 

 Species. Seven species of this genus have been discovered, six of them recently; 

 the seventh (j>lutonia Garman 1881) was usually referred to Raja until Breviraja was 

 recently separated from it, though the suggestion had been made in the original account 

 of the species that the rostral cartilage might remain undeveloped. For a Key to Species, 

 see p. 147.^ 



Breviraja atripinna Bigelow and Schroeder 1950 



Black-fin Skate 



Figures 62 (upper left), 63 



Study Material. One male and two females, 187-278 mm long, trawled by the 

 research vessel Atlantis off Santa Clara Province on the north central coast of Cuba 

 in 250-500 fathoms, in the Harvard Museum of Comparative Zoology.- 



Distinctive Characters. B. atripinna falls with B. sinus-mexicanus and with the B. 

 cui>ensis-a.nd-p/utoma group in that its tail is of a great length. But it is separable from 

 all three of these species by its relatively longer rostral cartilage. Halfgrown and larger 

 specimens also differ conspicuously from B. sinus-mexicanus in having a relatively much 

 longer interspace between the dorsal fins. Very young B. atripinna more nearly re- 

 semble B. sinus-mexicanus in this respect, but the tail of B. atripinna is so much less 

 thorny than that of the latter (cf. Fig. 63 with 69, 70) that there is little danger of 

 confusing the two. The plain coloration of its disc, without dark markings, is a con- 

 venient field mark for distinguishing atripinna from cuhensis and from plutonia. 



Description. Proportional dimensions in per cent of total length. Male, 225 mm, 

 and female, 278 mm, from Cuba (Harv. Mus. Comp. Zool., Nos. 36367 and 36370, 

 respectively). 



Disc: extreme breadth 44.5, 45-3; length 37.3, 38.5. 



Snout length: in front of orbits 8.9, 9.7; in front of mouth 12.0, 12.6. 



Orbits: horizontal diameter 4.0, 5.0; distance between 2.7, 2.7. 



Spiracles: length 2.2, 1.9; distance between 6.0, 6.1. 



Mouth: breadth 5.3, 5.0. 



Nostrils: distance between inner ends 5.8, 5.9. 



Gill openings : lengths, ist 1.3, 1.3; 3rd 1.3, 1.3; 5th 1.2, 1.2; distance between 

 inner ends, ist 9.8, 10. o; 5th 5.8, 6.1. 



First dorsal fn: vertical height 1.5, 1.3; length of base 4.2, 4.7. 



I. Bre-viraja combined with Raja. 



z. Atlantis Sts. 2985, 3443, 3459 (Harv. Mus. Comp. Zool., Nos. 36367, 36370 type, 36371). 



