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Show 232 DR. A. GUNTHER O N NEW AMERICAN FISHES. [Mar. 26, base; lower parts with numerous similar but more distinct white dots. This beautiful species, which I have named after Mr. Ford, is probably from Surinam. Four male specimens, the largest 9 inches long, were obtained from the collection of Dr. van Lidth de Jeude. CHAETOSTOMUS DEPRESSUS. D. 1/7. A. 6. P. 1/6. L. lat. 23. Head and trunk much depressed and flattened. The length of the head is rather more than one-third of the total (without caudal) ; the diameter of the eye is one-fifth of the length of the head, and two-thirds of the width of the interorbital space. The margin of the snout is covered with short bristles ; interoperculum with a bundle of about eight similar bristles, the longest being only half as long as the eye. The lower margin of the opercle slightly serrated. The lower side of the head, thora.x, and belly entirely naked. Dorsal fin rather higher than long, the first ray being shorter than the head ; the length of its base is nearly equal to its distance from the caudal; there are six scutes between the two dorsal fins. Caudal fin obliquely truncated, the lower rays being much longer than the upper. Pectoral spine extending to the second third of the ventral, and rather rough ; ventral fin extending to the end of the anal. Eleven scutes between the anal and caudal fins. Scutes with numerous strise, each stria composed of numerous very small spines. Posthumeral ridge obtuse. Brown, each scute with several round very small whitish dots; dorsal and caudal rays with a series of similar dots, the interradial membrane being immaculate. This species is also probably from Surinam ; one male specimen, 6 inches long, has been obtained from the collection of Dr. van Lidth de Jeude. This species is allied to Plecostomus barbatus and P. guttatus. W e have received a very complete series of the former species from the same collection, and I find that the long bristles on the margin of the snout and the interoperculum form a sexual character and are peculiar to the male. In the female they are very short, and sometimes scarcely developed. Both these species might be referred, with greater propriety, to Cheetostomus. CH.ETOSTOMUS MEGACEPHALUS. D. 1/7. A. 5. P. 1/6. L. lat. 23. Head but slightly depressed, rather longer than broad, its length being more than one-third of the total (without caudal); a very obtuse ridge runs from the upper angle of the orbit to below the nostril; occiput flat; interorbital space with a pair of shallow grooves. The horizontal diameter of the orbit is more than one-half of the width of the interorbital space, and about one-fifth of the length of the head. Margin of the snout granulated, without |
