196 PROCEEDINGS OP THE ACADEMY OP with one anterior on the peduncle. The first dorsal has two bands parallel with its upper margin ; the second has three narrower longitudinal bands. A single specimen of the species was found in the island of Trinidad, near the mouth of a river in the vicinity of the celebrated Pitch Lake. Description of a new South American type of SILUROIDS, allied to Callophysus. BY THEO. GILL. PlMELETROPIS Gill. Body naked, moderately elongated and compressed, tapering to the caudal. Head cuneiform in profile, depressed and ovate above, and sloping rapidly outwards. Supraoccipital extended longitudinally backwards, but not con-nected to a dorsal buckler. Eyes submedian and oblique. Barbels six, con-sisting of the maxillary and two pairs of mental. Branchial apertures large and continuous under the throat Branchiostegal rays generally eight. Mouth moderate and terminal ; upper jaw slightly protruding. Teeth uniserial, wide, straight and truncated. Lateral line straight and extending to the caudal ; anteriorly with lateral branches. Dorsal fin quadrangular, elevated anteriorly, and with its first ray simple and slender. Adipose fin elongated and cariniform. Anal fin similar in form to the dorsal, and under the adipose fin. Caudal fin deeply emarginated, and with equal and pointed lobes. Pectorals pointed, and with the superior ray simple and slender. Ventrals with the second ray longest. Pimeletropis agrees in almost all of its essential characters with Callophysus of Muller and Troscbel, but differs in the presence of the single row of teeth in each jaw. The same character, in connection with others, distinguishes it from Pimelenotus Gill. Pimeletropis lateralis Gill. The elongated and slender body is highest under the dorsal, and from its , termination the dorsal outline commences to slope backwards to the end of the long adipose fin, under the first half of which it is slightly curved, and then nearly straight ; the caudal peduncle is slender and elliptical, but at the base of the caudar fin it appears compressed and expanded superiorly and inferiorly, from the recurrence of the rudimentary rays of the fin. The greatest height is about a sixth of the entire length from the snout to the concave margin of the caudal fin ; that of the peduncle is little more than a third of the former. The lateral line is perfectly straight, and is anteriorly furnished with diverg-ing branches, which tend obliquely and posteriorly. The head is above of an oval form, and declines to the region of the poste-rior nostrils, in a slightly concave line, to the eyes ; the sides are posteriorly rounded near the skull, and thence descend obliquely outwards to the opercu-lar margin. The head, from the snout to the margin of the operculum, forms nearly a fifth of the total length, and its greatest breadth bears a relation to this length of fourteen to nineteen. The width regularly diminishes from this point to the angle of the mouth, where the proportion is as ten to nine-teen. The snout is obtusely horizontally rounded, and the space between the anterior and posterior nostrils is convex. The skin is mostly smooth, but papillae cover the space between the eyes and over the fontanelle ; there are also a few meandering dermal grooves be-low and behind the eyes. The supraoccipital process is linear, and four times longer than broad. The eyes are longitudinally oval and contracted by the skin ; the longitudinal diameter within the skin exceeds a seventh of the head's length ; their ante-[Aug.