434 FLOEENCE BUCHANAN. 



most of them are described in scattered journals, and some 

 have been overlooked by later writers on the group. 



The Acoetidse may be defined as elongate Polynoids, with the 

 elytra alternating regularly with dorsal cirri throughout the 

 body, except for the second and third pairs which are on 

 consecutive segments, the 4th and 5th respectively. The dorsal 

 surface of the body is generally transversely grooved, the grooves 

 being very fine and close together, often quite obliterating the 

 segment boundaries. The prostomium bears two large pupil- 

 lated eyes, generally on well-developed peduncles ; there may 

 be in addition smaller eyes or pigment spots behind them. 

 There is a single median prostomial tentacle and a pair of 

 lateral ones: the former is sometimes rudimentary or even 

 absent ; when present it springs from the posterior part of the 

 prostomium. The paired prostomial tentacles are also occa- 

 sionally absent ; when present they generally arise from the 

 ventral surface of the prostomium. There is a pair of palps, 

 usually very large and well developed. The parapodia of the 

 buccal segment have moved forward so as to lie in front of the 

 mouth; they consist each of a basal part bearing two peri- 

 stomial tentacles corresponding to the dorsal and vental cirri 

 of the other parapodia, and sometimes also bearing chaetae. 

 The parapodia of the following segments are either uniramous 

 or biramous with the notopodial lobe very small ; each one con- 

 tains a much-coiled dorsal chsetal sac, the " spinning gland " 

 of Eisig (6), producing numerous exceedingly long, fine, silky 

 capillary chsetse, which probably help to form the tube in 

 which the creature lives ; occasionally, however, the sac may be 

 shorter, and the chsetse produced in it more like ordinary chsetse, 

 projecting from the sac instead of being kept inside it. There 

 is a median ventral longitudinal ridge protecting the nerve- 

 cord ; it is bounded on each side by a deep furrow, and widens 

 in front just behind the mouth. The pharynx is exsertile, 

 papillose on the anterior margin; the jaws large and horny, 

 armed with two central and many lateral teeth. 



The known species of the sub-family are only fifteen in 

 number, and of most of these only single and incomplete speci- 



