50 DEEP-SEA FISHES OF THE ATLANTIC BASIN. 



sure of this fact). Eye surrounded by a cutaneous fold, which in a fresh specimen narrows 

 it very much, so that it measures only about one-twentieth of the length of the head. (The 

 size of the eye seems much greater, however, in a specimen preserved in spirits.) Gill open- 

 ing wide; the operculum covered in life by a membranaceous tegument. 



Skin naked. The lateral line begins at upper angle of gill opening, descending rapidly 

 to median line, after which it falls to the base of the caudal. 



Dorsal occupies four fifths of the length of the back, beginning above the upper angle 

 of the gill opening. Its anterior portion (two-thirds of its entire length) is composed of a 

 low, cutaneous, adipose, fold or cushion, while its posterior portion is a true fin supported by 

 rays. Anal extends to posterior portion of dorsal, though a little shorter and extending a 

 little further posteriorly. Caudal slightly emargiuate, and equal in length to about one- 

 sixth of the length of the body. Pectorals very short; the origin almost under that of the 

 rayed portion of the dorsal. • 



Color bluish ; iris white. 



Radial formula: D. 17; A. 14; P. 9; V. !>. 



The unique representative of this species was obtained off the coast of Morocco, in 

 1,400 meters. It is very small, and the action of alcohol has distorted it Aery much. Hap- 

 pily a sketch made from the fresh specimen has enabled M. Vaillant to give a figure and a 

 quite minute description. The length of the body is scarcely GO millimeters; its height is 

 about one-fifth of its length, and its thickness is still less. 



AULASTOMATOMORPHA, Alcock. 



Aulastomatomorpha, Ai.cock, Aim. and May. Nat. Hi>t.. vi, 307, (Oct. 1890), vn, 10, Jan. 1891, with outline 

 figure. Type, A. phospliorops. 



Body elongate, covered with minute, hardly imbricate scales. Head naked. Anterior 

 bones of head produced intoalongtube terminating in a narrow month. .Margin of upper jaw 

 formed by premaxillarics and mamillaries. Teeth uniserial and in the jaws only. Eye 

 large. Gill cover apparently complete. Gill opening wide below, contracted above, its 

 upper angle nearly on the level of the pectoral fin. Gills 4, with narrow laminae. Pseudo- 

 branchiae rudimentary. Dorsal fin upon the caudal peduncle. No adipose dorsal. Anal fin 

 very long. Caudal forked. Pyloric caeca few, small. No air bladder. 



This genus is characterized especially by the rudimentary pseudobranchise, and the 

 prolongation of the anterior bones of the head into a snout, like that of Aulostoma. 



The type of the species is A. phosphorous, Alcock (1. e.), obtained by the Investigator in 

 the Arabian Sea, station 104, at a depth of 1,000 fathoms; a single specimen, believed to be an 

 adult male, 11 inches in length. (Figure 55.) Alcock remarks that the head of this unique 

 fish is covered throughout by a thick, spongy, glandular skin, with dazzling white reflec- 

 tions, which is probably luminous in function. The eyes are very large and extremely 

 prominent. 



Family PTEROTHRISSID^E, Goode and Bean. 



Bathythrissidw, Gunther, Challenge! Report, xxu, 1887, 220. 



Body oblong, with rounded abdomen, covered with cycloid scales; head naked; bar- 

 bels none. Margin of the upper jaw formed by the iutermaxillaries mesially, and by the 

 maxillaries laterally. Opercular apparatus complete. Adipose fin absent; dorsal fin much 

 elongate, many-rayed; anal flu short. Stomach with blind sac; pyloric appendages numer- 

 ous. Gill apparatus well developed; pseudobranchise; gill openings wide; an air bladder. 

 Ova very small; ovaries without duct. (Giinther.) 



Theuame of the genus proposed by Giinther falls into synonymy, and the family name 

 is, in accordance with common usage, chauged to correspond to that of the typical genus. 



