226 Memoir Sears Foundation for Marine Research 



Distinctive Characters. The adult is separated from A. frofundorum, A. laurussonii 

 and A. atlanticus^* by the considerably greater size of its second dorsal relative to the 

 first, and by the fact that its first to third gill openings are about as long as the distance 

 between the nostrils but only about one-half that relative length in the other three species. 

 It is further separated from frofundorum (the only local species with which it might be 

 confused) by its relatively larger eye, and by the fact that Its caudal occupies about one- 

 third of the total length as compared to only about one-quarter. Young specimens of the 

 diflFerent species may be difficult to separate. 



Description. Proportional dimensions in per cent of total length. Female, 407 mm., 

 from Cuba (Harv. Mus. Comp. Zool., type. No. 36092). 



Trunk at origin of fectoral: breadth 10. i ; height 1 1.8. 



Snout length in front of: outer nostrils 5.85 mouth 9.3. 



Eye: horizontal diameter 2.7. 



Mouth: breadth 6.1 ; height 2.2. 



Nostrils: distance between inner ends 3.9. 



Labial furrow lengths: upper 2.1 ; lower 2.5. 



Gill opening lengths: ist 3.35 2nd 3.4; 3rd 3.2; 4th 3.O5 5th 2.1. 



First dorsal fin: vertical height 2.9; length of base 4.4. 



Second dorsal fin: vertical height 4.23 length of base 6.1. 



Anal fin: vertical height 3.7; length of base 13.7. 



Caudal fin: upper margin 33.O5 lower anterior margin lO. i. 



Pectoral fin: outer margin lO.i ; inner margin 4.9; distal margin 7.7. 



Distance from snout to: ist dorsal 47.85 2nd dorsal 57.7; upper caudal 67.O; pec- 

 toral 23.9; pelvics 40.2; anal 52.2. 



Interspace between: ist and 2nd dorsals 7.O5 2nd dorsal and caudal Indefinite; 



anal and caudal 0.0. 



Distance from origin to origin of: pectoral and pelvics 18.5; pelvics and anal 1 2.5. 



Trunk highest and broadest opposite axil of pectoral, narrowing evenly rearward. 

 Caudal peduncle strongly compressed laterally, about V2 as broad as deep. Body sector to 

 cloaca about as long as tail sector. Dermal denticles small in specimen examined, moder- 

 ately erect, leaf-like, with short pedicels, their blades with weak median crest but tridentate 

 free margin, the median tooth much the longest; the denticles slightly the largest, rela- 

 tively the narrowest, and the most closely spaced along upper sides of caudal. 



Head strongly flattened anteriorly, and contracted laterally just anterior to the 

 outer ends of the nostrils, its dorsal surface noticeably concave, with a triangular belt of 

 about 1 10 very prominent pores along the midzone anterior to eyes. Snout thin, broadly 

 rounded at tip, its length in front of mouth slightly less than y^. as great as distance from 

 its tip to 5th gill opening, its lower surface with a belt of conspicuous pores in 4 rows along 



14. The only other members of the genus yet known from the North Atlantic. 



