DISCUSSION OF SPECIES AND THEIR DISTRIIiUTION. 495 



til the i)iey swallowed, this cavity is suspended as a large sac, from the lower part of the 

 luxly, and tloats in the water. The upper and lower jaws are armed with a series of teeth, 

 wliich art! very unequal in lenj;th, some being- very long, others small, all are very slendei-, 

 aud can be depressed toward the inside of the uiouth. This peculiarity of the teeth may 

 be observed in the Lojili iux, in the pike, and numerous other rapacious fish with long slender 

 teeth. The vomer is armed with a. transverse series of single teeth, aud extends across the 

 whole width of the roof of the mouth ; the palatines aud pterygoid teeth are situated at 

 some distance behind the vomer, aud form two buiulles irregular in form. The pharynx 

 and (esophagus are, as might be expected, very wide. The eye is situated high up on the 

 side of the head; it is very small, covered by, but aiipearing tiirough, the skin. There are 

 uo nasal openings. The opercular lueces are leduced to styliform ludiments; there are 5 

 branchiostegals. Only the three inner brancliial arches bear short branchial iamellai, 

 which are disposed in a double series on the two middle ones, and in a single one on the 

 innermost arch. The gill opening itself is a slit of moderate widtli, beloW and behind the 

 pectoral fin. The ui)per surface of the head is concave, and in the middle of its anterior 

 portion there is situated the single filament to wiiich tiie anterior dorsal fin is reduced; 

 this filament is more than half as high as the head, aud dilated into a small lamella at its 

 extremity. The second dorsal flu occupies the back of the tail, and is comijosed of 14 

 simple rays, none of which are as high as the fin is long. The caudal fin is quite free from 

 the dorsal and anal, and composed of S very soft rays, which are, bifid at the, end, ami 

 form a convex posteiior margin. Anal fin very short, composed of 4 rays only, which are 

 opposed to the posterior dorsal rays. Tiie base of the pectoral fin is fieshy and enveloped 

 in skin, as in other rcdhuJiiti. It is composed of IS simple and feeble rays. Ventral fius 

 none. Vent situated immediately behind the abdominal sac. The whole fish, even the 

 inside of the mouth of the abdominal sac and of the stomach, is of a uniform black. 



Total length (mouth closed), '.'>.6 inches; length of intermaxillary and of mandible, 1.4 

 inches.' 



LIOCETUS, Giinther. 



Lwciliia [subgenus], Gunthek, C^halleiiger Report, xxii, 1887, 57. [Type, MelanoceUia Murrayi, Giinther.] 

 Tlie subgenus i/t»cc^«.v of (iiinther differs from McJanuvilus cliiefly in the absence of 

 vomerine teeth. 



LIOCETUS MURKAYI, Gl-ntukk. (Figun<407.) 



ilclanocciiix hinjihtosiiK, Gunthek., Study of Fishes, 1880, 473. (Name only.) 

 MiJaiiDcetiis (Lhicctus) Minraiji, GtiNTnKR Challenger Report, xxn, 1887, pi. XI, fig. A. 



Extremely similar to Mvkmocetus Johnsunii, but, singularly, there is no trace of vo- 

 merine teeth, whilst there is no distiuctiou between the two species as regards the den- 

 tition of the iaws. The posterior angle of tiie mandible projects more and forms a 

 salient point. The mouth is comiiarati vcly less wide, and the maxillary considerably shorter, 

 being about two-fifths of the total length, without caudal, whilst it is rather more than one- 

 half in the Madciran species. Eye rudimentary. One cephalii^ spine, which is shorter than 

 the maxillary. The last dorsal ray is connected by a sliort and delicate membrane witii 

 the caudal fin; nuistof tlu' caudal rays are bifid, the longest shorter than the maxillary. 

 Pectoral fin as nuich developed as in MvlaiKxrfus Johiixoiiii. 



Entirely black. 



r.iuea. 



Total length 44 



J^< ugth of mantlihle 14 



Length of maxillary 12 



Length of caudal fin lOi 



Radial formula: 1>. 1-13; A. 4; CD; F. U.— Giinther. 



A young specimen, 14 lines in length, was taken by H. M. S. ChaUcngtr in the niid- 



» GCntuer, Proc. Zoiil. See, 1861. 



