308 Mr. A. Alcock on the Bathyhial Fishes 



The snout is a little less than half the length of the head, 

 or 6§ in the total without the caudal. 



The eyes are very large and extremely prominent ; the 

 major diameter of the globus oculus is sliglitly over ^ the 

 head-length, but owing to the encroachment up to the mar- 

 gin of the cornea of the bi'oad posterior orbital fold, the 

 diameter of the exposed " eye " is only a little more than ^ 

 of the same standard ; the true (bony) interorbital space is 

 less than half the diameter of the eye in width. 



Nostrils situated high up, above the anterior orbital angle. 

 Mouth at the extreme end of the tubular snout, small, the 

 jaws apparently with limited motion. The upper jaw, which 

 projects slightly beyond the lower, is formed in its anterior 

 half by the premaxilla, in its posterior half by the maxilla. 

 Minute, acute, recurved teeth in a single row in the pre- 

 maxillaj and mandible ; no teeth in the maxillee. 



Gill-openings very wide below, contracted above, and not 

 surpassing the level of the pectorals. Gill-covers apparently 

 complete ; their constituent bones, including the branchio- 

 stegal rays, though well calcified, are extremely thin and 

 fragile, and are completely concealed within a continuous 

 uniform investment of confluent external skin and internal 

 mucous membrane. Four gills, with narrow laminae and 

 coarse lamellse ; the fourth gill-cleft wide ; gill-rakers well 

 developed on all the arches, moderately long on the first, 

 short on the fourth and fifth. Pseudobranchiai rudimentary, 

 consisting of four or five delicate short lamellce on each side. 



Body covered with minute, hardly imbricate, cycloid scales, 

 about jV by -gV of an inch respectively in the shortest and 

 longest diameters. The lateral line traverses tlie middle of 

 the body uninterruptedly. 



The dorsal fin begins slightly in advance of the posterior 

 fourth of the body measured without the caudal ; the length 

 of its base is shorter than the snout ; its rays, like those of 

 the anal, increase gradually in length from before backwards, 

 the longest, being not quite equal to the major diameter of the 

 bulbus oculus. The anal begins an eye-length behind the 

 vertical through the middle of the body as above limited, and 

 ends a short distance behind the vertical through the poste- 

 rior limit of the dorsal ; its longest rays slightly exceed the 

 longest dorsal rays. Caudal symmetrically forked, its rudi- 

 mentary rays very numerous, both dorsally and ventrally. 

 Pectorals narrow, rather more than \ of the head in length. 

 Ventrals short, arising immediately behind the vertical 

 through the middle of the body, as above limited, and 

 reaching just behind the vent. 



