Cope.] "t> [Jan. 5, 



Color, light brown. The dorsal fin is sparsely and the caudal fin is 

 closely spotted with blackish, and the spinous rays of both are light 

 colored with dusky spots. 



Total length, 53 mm. ; length to basis of caudal fin, 41 mm. ; length to 

 base of anal, 25 mm. ; length to base of ventrals, 16 mm. ; length to line 

 connecting l)ase8 of pectorals, 10 mm. 



A single specimen from the Rio .Jacuhy, Rio Grande do Sal. 



This is the third species of the genus now known, the one first de- 

 scribed being the H. notatus of Eigenmann.* This species is said to 

 be characterized by the presence of a triangular posterior process of 

 the occipital element, and by the compressed and elevated form of the 

 head ; characters not seen in the present species. The orbit is smaller, 

 but the interorbital space is only as wide as three of its diameters. It has 

 only twenty -five plates of the lateral line. The Hisonotus nigricaudaj; of 

 Boulenger differs in the twenty-five plates of the lateral line, the I. 5 

 pectoral rays, the more numerous rows of ventral plates and the larger 

 eye. 



Hisonotus leptochilus sp. nov. 



Form rather slender ; head rather depressed. Depth at first dorsal ray 

 entering length to base of caudal fin, 5.5 times. Eye small, entering 

 length of head 5.5 times, and three times on the rather flat interorbital 

 space. Venter covered with from ten to twelve rows of scuta, a single 

 row on each side anteriorly, larger than the others. Caudal region 

 rounded above and below. Hispid everywhere, especially on the super- 

 temporal region. Three transverse and a median rhombic scuta between 

 the occipal scute and the base of the dorsal spine. Lower lip thin, with 

 thin transverse posterior margin and inconspicuous tubercles. 



Dorsal fin originating a little posterior to ventrals. Pectorals reaching 

 middle of ventrals ; ventrals barely reaching anal. Inferior angle of 

 caudal fin a little longer than the superior. Radii, D. I. 7 ; P. I. 6 ; V. I. 

 5 ; A. I. 5. Scales of lateral line, 2S. 



General color dusky, with numerous small pale spots everywhere, most 

 conspicuous when the fish is immersed in fluid. Fins lighter, conspicu- 

 ously spotted with dusky. 



Total length, 54 mm.; length to base of caudal fin, 44 mm. ; length to 

 base of anal, 35.5 mm. ; length to base of ventrals, 17.5 mm. ; length to 

 base of pectorals, 10 mm. ; interorbital width, 6 mm. 



The important characters which distinguish this species from the H. 

 Icevior, are the thin and truncate lower lip with feeble tuberculatiou ; 

 the numerous ventral plates ; the narrower interorbital space, and the 

 greater hispidity, especially of the head. It differs from the II. notatus in 

 much the same way as the If. Icevior. 



* " Revision of South American Nematognatlu," California Acad. Sciences, ISOO, p. 391. 

 t Proceeds. Zo'ol. Sue, London, 1891, p. 231. 



