6 PROCEEDINGS OF THE Is^ATIONAL MUSEUM vol.84 



hypertroph}' of the lips is not noticeable, but on close examination 

 the lips show thickening, and the triangular points have just begun 

 their development. The ground color is pale brownish, marked with 

 14 conspicuous, vertical, dark bands, the first through the eye and 

 the last on the base of the caudal. Each bar that abuts on the dorsal 

 or anal forms a basal spot on the fin. On the dorsal these basal 

 spots are carried outward and anteriorly on the fin as a bar. Caudal 

 faintly spotted. Pectorals plain. Pelvics with membrane faintly 

 brownish. Dorsal fin lappets tipped with brown. Both specimens 

 have dorsal XVIII-10, anal III-7, and lateral lines 12 + 14, while the 

 lateral scales are 34 and 33. 



PERISSODUS GRACILIS, new species 

 Plate 1, B 



Holotype. — U.S.N.M. no. 84123, 46 mm in standard length, from 

 Kigoina, Lake Tanganyika; collected in February 1920 by H. C. 

 Raven. 



Paratypes. — U.S.N.M. no. 102111, two specimens, 48 and 55 mm in 

 standard length ; same locality data as holotype. 



Since its description by Boulenger in 1898, the genus Perlssodus 

 has been known only through the single 100 mm type specimen of 

 P. microhpis in the British Museum. The discovery of three exam- 

 ples in Mr. Raven's collection is therefore of great interest. These 

 specimens differ markedly from Boulenger's description in a few 

 points. In view of our lack of knowledge of specific variation in 

 P. mj.crole'pis^ I have hesitated to describe my examples as new, but 

 the differences, though small, appear to be fairly constant in the 

 three, and are similar in character to those that have been found 

 to be of specific value in other Tanganyika cichlids. 



Diagnosis. — Differs from Perissodus Tnicrolepis in having a greater 

 number of gill rakers, smaller mouth, more slender form, more 

 numerous soft anal and dorsal rays, 17 instead of 18 dorsal spines, 

 slightly smaller scales, a different lateral line count, and longer 

 pelvic fins. In the peculiar dentition, the thick lips, and most gen- 

 eral characters, the species is similar to P. microlepis. The head 

 length is proportionally about the same as in P. mici'olepis^ and since 

 these specimens are much smaller than the type of that species, it 

 might be suspected that the proportional head length in adults of 

 gracilis would be smaller than in Boulenger's species. 



Description. — Depth of body somewhat over 4 in standard length, 

 length of head 3.3 to 3.4. Head 2.3 times as long as broad; snout 

 a little broader than long, a little longer than eye, which is 3.1 to 

 3.4 times in length of head and is equal to or longer than the bony 

 interorbital. Lower jaw projecting maxillary extending barely to 



