DISCUSSION OF SPECIES AND THEIR DISTRIBUTION. 49 



The genus is closely allied iii Xenodermichthys, but is easily distinguished from it 1>\ its 

 general appearance, its smaller mouth, and by the great inequality in the extent of the dor- 

 sal and anal tins. The skin, entirely devoid of scales, adheres hut slightly to the tissues 

 which it covers. 



LEPTODERMA MACROPS, \ aii.iani. (Figure 56.) 



Leptoderma maerops, Vaili.ani, Exp. Sci. Travailleur el Talisman, Poissons, 105, pi xn, fig. 2. — AXCOCK, 

 Ann. and Mag. Nat. Hist.. 1892, II, 361. 



Mody elongate, its greatest height just behind the head being equal to one-tifteenth of 

 its length, and its thickness at the same place in about the same proportion. It is slightly 

 thinner about its middle, and posteriorly the compression is much more decided. 



Head small but for enormous size of orbital spheres; its length one-fifth that of the 

 body; snout is obtuse, short, its length, hardly three-elevenths of distance separating its 

 extremity from posterior margin of opercular (lap: mouth small, the maxillarynot reaching 

 nearly back to the line of the anterior margin of the orbit. Each premaxillary armed with 

 a row of small conical teeth to the number of about four; maxillary toothless, the mandible 

 armed with teeth like those on the premaxillary, slightly developed, scarcely visible 

 except when strongly magnified; no teeth on the palatines. Iris is much developed, pro- 

 truding; diameter of eye is three-eighths length of head. Gill openings wide and low. 



Ventral far forward, at a distance from snout equal to about three-eighths length of 

 body; lateral line apparently lacking; the tegument is so delicate that it has been impos- 

 sible to find a specimen in which it was not destroyed, since it adhered but slightly to the 

 muscular tissues. Dorsal and anal very low, unequal in extent, the origin of the former 

 opposite twenty-second ray of the latter, both terminating at about the same vertical and 

 close to the caudal. All the rays are divided and articulated. Caudal but slightly devel- 

 oped; pectoral lanceolate; ventrals seemingly connate. 



Color, black, velvety; iris, gray; pupil, opaline. 



Radial formula: D. 48; A. 71; V. 5. 



This species appears, like Xenodermichthys, to occur in large schools upon the Banc 

 d'Arguin, 47 specimens having been taken in one haul at a depth of 1,495 meters. Others 

 were obtained in the same locality at 2,330 meters, and also on the coast of Soudan at 1,100 

 meters, and the coast of Morocco at 1,163 to 1,23") meters. M. Yaillant complains that not- 

 withstanding the abundance of specimens not one of them was in condition for description. 



The Investigator obtained at station 134, in the Indian Ocean, 753 fathoms, a fish SjJ 

 inches long, identified by Alcock with this form. 



ANOMALOPTERUS, Vaillant. 



Anomaloptt nix, Vaillant, Exp. Sci. Travailkur et Talisman, Poissons, 1888, 160. 



Body oblong, short; head very large. Teeth upon premaxillaries, mandible, and pala- 

 tines. Soft dorsal and anal upon the caudal peduncle, nearly equal in extent, the former 

 preceded by a kind of adipose fold or cushion, occupying the entire length of the back in 

 front of it. Gill opening broad and large. Skin naked. 



In its deprivation of scales the genus resembles Xenodermichthys and Leptoderma, from 

 which, however, it is distinguished by its general form and by the adipose ante dorsal cush- 

 ion, which occurs in no other genus. 



ANOMALOPTERUS PINGUIS, Vaillant. (Figure 54.) 



Anomalopierui pinguis, Vaillant. Exp, Sci, TtavaiUeur et Talisman, Poissons, 1888, 160. 



Head nearly half entire length of body; length of snout one-third that of the head. Mouth 



very wide, the maxillary extending beyond perpendicular from posterior margin of orbit. 



Upper jaw and mandible armed with small teeth; stronger teeth upon palatines; none upon 



the vomer (the small size of the individual examined renders it impossible to be absolutely 



19868— No. 2 1 



