218 
MEMOIRS OF THE QUEENSLAND MUSEUM. 
Described and figured from the lectotype of Pomacentrus onyx De Vis, a 
specimen 34 mm. in length from snout to hypural joint, selected from a series of 
seven co-types, 21-39 mm. (Qld. Mus. Regd. No. 1. 11/99.) 
Locality 44 South Seas.” Collected by Captain Browne. 
Note. — Chcetodon araneus Bennett 28 from Ceylon is the Dascyllus aruanus 
“ varieteit met eene zwarte staartvin” of Schlegel & Muller, 29 and appears to be 
sped fically^disti net from TetradracJi mum melanurus (Bleeker). 
Text-fig. 1. — Tetradr actinium melanurus (Bleeker). Lectotype of Pomacentrus onyx De Vis from 
the “ South Seas.” (The usual dark bands have completely faded from De Vis’ types, so- 
cannot be included in this figure.) 
G. P. Whitley , del. 
MECVENICHTHYS, gen. nov. 
Orthotype . — Heliastes immaculatus Ogilby. 
Eye large. All opercles entire. No preorbital spine or notch. Top of head 
scaly to level of nostrils. Suborbital naked, not adnate to cheek. A single series 
of well-developed, fixed teeth in each jaw ; each tooth is slightly curved, subcylin- 
drical near its base with a bluntly pointed tip, and is not fused with its neighbours, 
nor are there gaps between the teeth. Gill-rakers short. 
Body deep, compressed, suborbicular, scaly. Caudal peduncle short and 
broad. Ctenoid scales in less than thirty transverse series, extending on to all the 
fins except ventrals. Thirteen dorsal spines. Base of soft dorsal nearly half length 
28 Bennett, Fish. Ceylon, Feb. 1830, p. 17, pi. xvii. 
29 Schlegel & Muller, V'erh. Nat. Ges. over/., Pise., 1844, p. 21. 
