302 DR. A. GUNTHER ON A NEW FISH FROM MADEIRA. [June 28, 
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 spmous 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. (PI. XXV.) 
Deljl4e0C: 8) cAo4S eBets. 
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 aright 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 obsérved in the Lophius, 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 cesophagus 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 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 lamellze, 
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 
fin is reduced; this filament is more than half as high as the head, 
and dilated into a small lamella at its extremity. The second dorsal 
fin occupies the back of the tail, and is composed of fourteen 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 eight very 
