228 PERCY SLADEN TRUST EXPEDITION. 



58. Fseucloplesiops ti/pus, Blkr. 



The first example of this monotypic genus to reach the British Museum was taken at 

 Diamant at a depth of 16 fathoms, and shows that only the first ray of the dorsal and 

 anal fins is a true spine, which is followed in each case hy a number of simple articulated 

 rays. Each ventral fin is made up of a slender spine and 4 simi)le articulated rays. 

 The o-enus appears to be allied to Pseiidochromis and to Pies lops. 



Chagos Achipelago, Peros, off" Diamant Island. 



Centrarchidse. 



59. Kuhlia tcenitora, C. & V. 

 Seychelles Group, Praslin. 



MuUidse. 



60. Upeneoides tragula, Richards. 

 Maldives, Mulaku, 27 fathoms. 



ChsetodontidsD. 



61. Solacanthus somervillii, sp. u. (Plate 24. fig. 6.) 



Depth of body 2 in the length, length of head 3|. Snout f as long as eye, the 

 diameter of which is 2f in the length of head and equal to the interorbital width. 

 Pr^orbital denticulated ; prseopercular spine | the length of head ; no spines on lower 

 limb of prajoperoulum or on inter operculum. 50 scales in a longitudinal series. Dorsal 

 XIV 16 ; spines increasing in length throughout ; length of base of soft-rayed part If 

 in that of the spinous part. Anal III 17. Soft dorsal and anal obtusely pointed. 

 Caudal rounded. Pectoral nearly as long as the head ; ventrals extending to the origin 

 of anal. Dark brownish; a large blackish humeral spot; body with several irregular 

 narrow dark transverse bars directed somewhat obliquely downwards and forwards, 

 each occupying the whole width of a transverse series of scales, but changing in its 

 course from one series to another ; fins blackish, the caudal with a narrow pale edge. 



Seychelles Group, Coetivy. 



A single specimen, 64 mm. in total length. 



Closely allied to S. nmlUspmis, Gthr. & Playf., which has 2 praeopercular spines, 

 the upper I the length of head, and 3 or 4 interopercular spines. 



Named after Comm. Boyle T. Somerville, R.N., who commanded H.M.S. Sealark 

 during the expedition. 



Acanthuridse. 



62. Acantlnirus tiHosteffus, Bl. 

 Seychelles Group, Coetivy. 



Pomacentridse. 



63. Dascyllus nigripinnis, sp. n. (Plate 24. fig. 5.) 



Depth of body If in the length, length of head ^\. Snout shorter than eye, the 

 diameter of which is 2| in the length of head and equal to the interorbital width. 



