Dr. A. Gunther on a new Genus of Pediculate Fish. 333 



as Saccopharynx and Alepidosaurus. When brought to Mr. Johnson, 

 the belly was much distended, and contained, rolled up spirally 

 into a ball, a Scopeline fish, which measured 7^ inches in length, 

 and 1 inch in depth. Nevertheless it was tempted to take a 

 bait. 



Melanocetus. 



Head and body compressed, head very large, body small, abdo- 

 minal cavity forming a sac suspended from the trunk. Cleft of the 

 mouth exceedingly wide, vertical. Teeth of the jaws and palate 

 long, pointed, unequal in size. Skin smooth. The spinous dorsal 

 is reduced to a single filament placed on the head. The soft dorsal 

 and anal short. Ventrals none. Slit of the gill-openings of mode- 

 rate width, below the pectoral. 



Melanocetus Johnsonii. 



D. 1|14. C. 8. A. 4. P. 18. 



This singular fish is distinguished by a greater disproportion of 

 the various parts of its body than is found in the other genera of the 

 family to which it belongs. The head is of a tetrahedral form, and is 

 the most extensive part of the whole animal. The gape is enormous; 

 and although the lower jaw is vertical when the mouth is closed, it 

 can be moved downwards at more than a right angle. The lateral 

 extensibility of the mouth is not less than the vertical ; so that the 

 prey which can be received within the cavity of the mouth actually 

 may exceed the size of the fish itself. This enormous head is 

 followed by a very small trunk and tail, the length of both being 

 less than the depth of the head. As the trunk would not offer suf- 

 ficient room for an abdominal cavity corresponding in size to the prey 

 swallowed, this cavity is suspended as a large sac from the lower 

 part of the body, and floats in the water. The upper and lower 

 jaws are armed with a series of teeth which are very unequal in 

 length, some being very long, others small ; all are very slender, and 

 can be depressed towards the inside of the mouth : this peculiarity 

 of the teeth may be observed in the LopkiuSi in the Pike, and nu- 

 merous other rapacious fish with long slender teeth. The vomer is 

 armed with a transverse series of single teeth, and extends across the 

 whole width of the roof of the mouth ; the palatine and pterygoid 

 teeth are situated at some distance behind the vomer, and form two 

 bundles irregular in form. The pharynx and oesophagus are, as might 

 be expected, very wide. The eye is situated high up on the side 

 of the head ; it is very small, and covered by, but appearing through, 

 the skin. There are no nasal openings. The opercular pieces are 

 reduced to styliform rudiments ; there are five branchiostegals. 

 Only the three inner branchial arches bear short branchial lamellae, 

 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 width, below and behind the pectoral fin. The upper 

 surface of the head is concave, and in the middle of its anterior por- 

 tion there is situated the single filament to which the anterior dorsal 



