294 A MONOGRAPH OF THE AUSTRALIA^- APHRODITE A, 



Specimens of this species were dredged at a depth, of 5 fathoms 

 in Port Denison, and in Port Molle at 15 fathoms, during the 

 cruise of H.M.S. " Alert " on the Queensland Coast. 



The peristomium, as in many other species of Polynoe, is armed 

 with an aciculum. The oesophagus exhibits, when retracted, a 

 number of narrow longitudinal folds ; the epithelium is thickly 

 pigmented, and bears a strong resemblance to the hypoderm. 

 The gizzard is extremely powerful ; the teeth large, triangular 

 and subacute. The intestinal walls exhibit a longitudinal folding 

 of the mucous membrane, such as I have not noticed in any other 

 species of Polynoe. The CEeca are given off from the dorsal 

 aspect of the intestine ; a short neck leads into a tolerably 

 spacious sac, which gives off upwards a branch ending under the 

 dorsal integument, then curves towards the base of theparapodium, 

 where it ends in the ventral portion of the caecum. A pseudo- 

 heeraal system is evident. In a female young ova were observed 

 to be developing both around the cseca and round the ventral 

 pseudohsemal trunk. 



Fam. sigalionina. 



Genus Thalenessa, Baird. 

 Thalenessa microceras, sp. n. (PL XL, figs, 4 — 8.) 



The only specimen of this species which I have obtained is 

 incomplete, but contains over 70 segments. The head presents 

 in front a very minute process, which seems to represent a mesial 

 tentacle ; behind are the two pairs of sessile eyes placed close 

 together. The tentacular cirri consist each of a stout base or 

 peduncle and two rami — a ventral and a dorsal — about equalling 

 the peduncle in length, cylindrical and tapering ; the peduncle 

 presents near its base on the dorsal aspect, just in front of the 

 mesial tentacle a minute conical appendage ; at its distal extremity 

 are a few fine setse. Inserted close behind these are the extremely 

 elongated, smooth, tapering buccal tentacles. The first pair of 



