252 PEECY SLADEN TEUST EXPEDITION. 



167. Balistes viridescens, Bl. Sclm. 

 Maldives. 



168. Monacanthus oculatus, Gthr. 

 Maldives, S. Nilandu, 30 fathoms. 



169. Ilonacanthus nematophorus, Gthr. 



Maldives, Suvadiva, 43 fathoms, and Mulaku, 27 fathoms ; Seychelles Group, 

 Amirante, 30 fathoms ; Cargados Carajos, 20 to 30 fathoms. 



170. Ilonacanthus oblongns, Schleg. 



Seychelles Group, Amirante, 30 fathoms ; Cargados Carajos, 20 to 30 fathoms. 



171. Ilonacanthus melanistius, sp. n. (Plate 31. fig. 4.) 



Depth of body about 2i in the length, length of head 3. Saout produced, with 

 concave upper profile; upper angle of gill-opening nearly in the vertical from posterior 

 edge of eye. Scales papilliform. Dorsal spine 4-sided, with 4 series of barbs, inserted 

 over the middle of eye, when depressed reaching the origin of the second dorsal fin, wliich 

 has 33 or 34 rays, the middle of which are the longest, nearly f as long as the spine. 

 Anal 30-32. Caudal rounded. Ventral spine immovable. Body Avith small scattered 

 round dark spots ; membrane of spinous dorsal blackish ; caudal with irregvilar dusky 

 bars. 



Plankton, surface, near Parquhar Atoll. 



Three specimens, the largest 60 mm. in total length. 



Allied to the Australian M. peronii, Hollaad. 



172. Ilonacanthus setifer, Benn. 

 Seychelles, 37 fathoms. 



173. Pseudaluteres wasicorwi*, Schleg. 



Maldives, Suvadiva, 37 fathoms ; Seychelles Group, Amirante, 30 fathoms. 



Ostraciontidae. 



174. Ostracion cornntus, L. 

 Cargados Carajos, 20 to 30 fathoms. 



175. Ostracion coucatenatus, Bl. 



Seychelles Group, Amirante, 30 fathoms ; Cargados Carajos, 20 to 30 fathoms. 



176. Ostracion fornasini, 'Bianci. 



Seychelles Group, Amirante, 30 fathoms ; Cargados Carajos, 20 to 30 fathoms. 



