182 . AET. IL A. TZUKA : 



protruded condition the proboscis shows a series of soft papillae 

 on the anterior margin, and a little behind these one or more hard 

 prominent teeth. It terminates posteriorly in the proventricnlas, 

 a region more or less barrel-shaped and with wall marked with 

 in a longitudinal rows of dots. The proventriculus is followed 

 by a short tract which fi'equently tapers posteriorly and which 

 ends in a dilated part often provided with two lateral cseca and 

 marked off from the intestine behind by a constriction. Body 

 terminating posteriorly with two cirri. The minute parapodia have 

 dorsal and ventral cirri, of which the latter may however be absent ; 

 they are uniramous and bear falcate bristles with a terminal process, 

 which is either simple or bifid. Swimming dorsal bristles also 

 occur in the sexual form. E. Grübe has described the stolon as 

 having a few segments, two or three tentacles, two palpi, and 

 some tentacular cirri, besides two eyes which are generally large. 

 Parapodia with two fascicles of bristles, of which some are com- 

 pound, and others simple and long. Cirri present or absent. 

 Proboscis and proventriculus absent. 



Key to the genera found in Japan. 



a.' Tentacles and cirri very long and slender ; number of segments ie^^'. 



Aiiiblyosyllis. 



a." Tentacles not long, segments numerous. 



h.' Proboscis with a single, large, anteriorly situated tootli Syllis. 



h." Proboscis with a large tooth, accompanied with a trex^an. 



TrypanosylUs. 



Genus Ainhlyo syllis Grube. 



Prostomium short. Eyes four, the two on each side confluent. 

 Tentacles and cirri long and slender. Palpi small, appearing as 

 two bosses on the ventral surface. Two nuchal flaps. 



