48 DEEP-SEA FISHES OF THE ATLANTIC BASIN. 



much greater than half the diameter of the eye. The ventral origin is equidistant from the 

 posterior margin of the eye and the base of the posterior dorsal ray ; it is slender, and reaches 

 nearly, if not quite, to the vent. Color, uniform blackish. 



A single specimen (No. 33551, 17. S. N. M.), 3j inches in length, was obtained by the 

 Albatross at station 2099 in 37° 12' 20" N. lat., 69° 39' W. Ion., at a depth of 2,919 fathoms. 



ALEI'OSOMI'S SOCIALIS, i Vaii.lant), Goode and Beajs. (Figure 58.) 



Xenodermiehthys sucialis, Vaillant, Exp. Sci. Travailleur et Talisman, 18*8, 162, pi. xin, fig. 1. 



Body compressed, with upper and lower outlines parallel for the greater portion of their 

 length. Its length is nearly G times its height. 



Head one fourth of leugth of body. Snout very short, hardly one-fourth length of the 

 head, while the mandible, which extends considerably beyond the upper jaw, is nearly half 

 as long as head. The maxillary reaches nearly to the line of the center of the eye. Small 

 teetli upon the mandible and premaxillary. The palatines, the tongue, and the pharyngeal 

 bones are toothless. The eye is enormous, its diameter two-fifths of the length of the head. 

 It protrudes above, the profile, forming a protuberance noticeable either at the side or from 

 below. Width of interorbital space scarcely one-sixth of the length of the head. Gill 

 opening large, although the opercular slit does not reach very far up, its upper edge beipg 

 attached to the body by a membrane. 



In the fresh individual the skin was slimy, covered by a thick mucus, so that the lateral 

 line can not be distinguished; is doubtless merged in the fold between the upper and lower 

 muscular masses. No trace of scales. Vent situated behind middle of body. 



The dorsal extends behind the caudal peduncle; it is not very high and is slightly raised 

 posteriorly in relation to the dorsal outline. The anal resembles it precisely in size and 

 shape; the caudal is deeply emarginate, and is preceded above and below by very distincl 

 accessory rays, which occupy half of the distance between the dorsal and the anal. The 

 paired tins are but little developed, short, and the pectorals have about Hi rays. 



Color uniformly deep blackish, violet : the litis seem lighter on account of their trans- 

 lucency. There are traces of black spots upon the membrane of the anal, and also under 

 the eye upon the cheek and the opercular (lap, and these continue also upon the belly; 

 these spots are more conspicuous in the specimen when it is preserved than when it is fresh. 

 The iris is violet; pupil opaline. ( Vaillcmt.) 



This species was obtained in great abundance on the Banc d'Arguin, where 133 specimens 

 were obtained in one haul, at a depth <>t' 1,230 meters. It was also obtained in small numbers 

 off the coast of Morocco from 717 to 1,350 meters, and on the coast of Soudan at 800 meters. 

 Vaillant seems to be somewhat uncertain whether or not this form belongs to the genus 

 Xenodermichthys, aud remarks that, comparing it with the diagnosis of Dr. Giinther, he can 

 see nothing which absolutely rules it out. Assuredly, the skin presents no traces of rugosities 

 nor of any growth which can be compared to scales even in a rudimentary condition. At, all 

 events, it can be readily distinguished from Xenodermichthys nodulosus of Giinther, which 

 has an arrangement of fins very different, and a much slighter development of the eye. 



As Vaillant says, the great abundance in which this fish was taken in one haul of the 

 deep-sea net would seem to indicate that it occurs in large schools in the depths of ocean. 



Xenodermichthys Giiii/litri, Alcock, Ann, and Mag. Nat. Hist., 1892, n, 357, vol. 

 xvili, fig. 3, from Investigator, station 133, Indian Ocean, 078 fathoms, seems likely to 

 belong to this genus. 



LEPTODERMA, Vaillant. 



Leptodenna, Vaillant, Exp. Sci. Travailleur et Talisman, Poissons, 1888, 165. 



Body elongate, gradually diminishing posteriorly until it becomes almost thread-like. 

 Head moderate, but (in the only known species) with enormous eyes. Mouth small. Teeth 

 upon premaxillaries and maxillaries. A distinct submaxillary. Dorsal and anal elongate, 

 extended upon the caudal peduncle and ending slightly in advance of its extremity, the tins 

 very much larger than the dorsal. Gill opening wide, though not very high. No scales. 



