452 Bulletin 47, United States National Museum. 



seas ; but one species known until recently, when 6 genera and numerous 

 species have been described from the abyssal fauna? of the mid-Atlantic 

 and Pacific. (Alepocephalidce, G ANTHER, Cat., vn, 477, 1868.) 



a. Scales well developed, cycloid; teeth small; lateral line present. 

 b. Ventral fins well developed. 



c. Mouth small; maxillary with teeth; body rather deep. 



d. Dorsal and anal rather short, of 15 to 17 rays, similar to each other; opercular 



flaps long; head large. ALEPOCEPHALUS, 224. 



dd. Dorsal and anal longer, of 20 to 25 rays each, the anal the longer; opercular 

 flaps moderate. MITCHILLINA, 225. 



cc. Mouth rather large, moderate; body more elongate. 



e. Anal not longer than dorsal; teeth on palatines; maxillary with teeth. 



/. Dorsal longer than anal and inserted far in front of it. 



BATHYTROCTES, 226. 

 ff. Dorsal scarcely longer than anal and inserted nearly opposite it. 



TALISMANIA, 227. 



ee. Anal twice as long as dorsal; body rather elongate; jaws strong; no palatine 

 teeth. CONOCARA, 228. 



bb. Ventral fins wanting; body short, compressed; -naxillary with teeth; scales keeled. 



PLATYTROCTES, 229. 



aa. Scales wanting; skin thick, rugose, with nodules; no lateral line; teeth minute; ventral 

 fins present. ALEPOSOMUS, 230. 



224. ALEPOCEPHALUS, Risso. 



Alepocephcdus, Kisso, Mem. Ac. Nat. Sci. Turin, xxv, 270, 1820, (rostralus). 



Body oblong, compressed. Mouth rather small, the snout somewhat 

 prolonged; jaws nearly equal in front; a series of small teeth in each 

 jaw and on the vomer and palatines. Eye very large. Gill membranes 

 entirely separate. Branchiostegals 6. Opercular bones thin, the opercle 

 with extended membranous flaps. Dorsal low, not very long, with a 

 scaly base, similar to the anal ; pectorals and ventrals moderate ; caudal 

 moderately forked. Scales rather large, thin and cycloid ; no phospho- 

 rescent spots. Color violet black. Deep-sea fishes, found in most parts 

 of the ocean, (a, privative, without ?rof, scale; /ce<pa/l^, head.) 



a. Head one-third of total length or nearly so ; scales not minute. D. 15 to 17 ; A. 17. 



5. Scales moderate (in about 67 series). Snout 9 in body; eye 4 in head. PRODUCTTTS, 744. 

 bb. Scales small (in about 90 series). Snout 11 to 12 in body. 



c. Eye 3% in head ; pectoral 3% in head, about as long as eye. AGASSIZII, 745. 



cc. Eye 4^ in head ; pectoral 2% in head, much longer than eye. TENEBROSUS, 746. 



744. ALEPOCEPHALUS PRODUCTUS, Gill. 



Head 2 ; depth 4; eye 4; snout 3. D. 17; A. 17; scales 9-67-12. 

 Resembling A. agassiziiin form and proportions, but with larger scales, 

 smaller eye, and longer snout. Body quite robust, its height at the pec- 

 toral origin nearly one-fourth length from snout to base of median caudal 

 rays. Least height of the tail about one-half length of body. Posterior 

 margin of orbit nearly equidistant between snout and opercular margin ; 

 upper jaw extending a little behind vertical from posterior margin of 

 pupil ; lower jaw shorter and included, nearly one-half as long as the head. 

 Interorbital width 7 in head ; width behind the orbits less than 3. Insertion 

 of dorsal above vent, length of its base twice diameter of eye; aiial 



