138 

 113. Polyipnus SpiflOSUS, Griinther. 



Polyipnus spinosuss, Giinther, Challenger Deep-Sea Fishes, p. 170, pi. li. fig. B : Alcook, Ann. Mng. Nat. Hist., 

 Dee. 1889, p. 398, and Aug. 1891, p. 126 : Gilbert and Cramer, Proc. U. S. Nat. Mus. XIX., 1896, p. 416. 



D. 12-13. A. 15-16. P. 12. Y. 5. 



Body oval, its greatest height between two-thirds and three-fourths its 

 length without the caudal. Major diameter of eye vertical, more than half the 

 length of the head. Snout very short. Nostrils large, situated close together 

 on top of the snout, the posterior the larger. 



The upper part of the head is narrow compressed and concave, and is 

 bounded on each side by a serrated ridge that ends in a large sharp semi-recumb- 

 ent spine. The edge of the preoperculum is serrated near the angle, which is 

 occupied by a claw-like spine pointing vertically downwards. The lower edge 

 of the mandible is finely serrated and ends in a spinule. 



The scutes along the mid-ventral line are spiny. 



The dorsal fin is preceded by a small forked spine: the adipose dorsal 

 occupies the middle of the space between the dorsal and caudal. The pectoral 

 reaches almost as far as the base of the ventrals. 



The luminous organs are as follows, on each side : — 



(1) a series of six small ones in the intervals between the bases of the 

 branchiostegal rays : 



(2) a series of six larger ones along the isthmus : 



(3 1 a series of ten still larger ones along the abdomen between the humeral 

 symphysis and the base of the ventral fin : 



(4) a series of five between the ventral and the anal : 



(5) a series of twelve above the anal fin : 



(6) a series of four or five along the ventral border of the caudal peduncle : 



(7) a small one at the anterior angle and a small one at the posterior angle 

 of the eye : 



(8) a very large one below the middle of the orbit, on the preoperculum : 

 ( ( .t) a small one on the suboperculum : 



(10) two above the base and three behind the base of the pectoral fin, these 

 form a second tier on the abdomen : 



(11) one behind the gill-opening and one much further back, forming a 

 third tier on the abdomen. 



The scales are extremely thin and deciduous : one from the side of the trunk 

 is 7'"> millim. in vertical and about 25 inillim. in horizontal diameter; one from 

 the middle of the tail is 6"5 millim. and not quite 2 inillim. in its diameters. 



The largest specimen is between 2 and 2- inches long. 



