[13] ANNELIDS OF PROVINCETOWN, MASS. 711 



Marentzeller figures the setae of Syllis ochracea as bidentate; Marion- 

 Bobretzky represent the same setse as ending in a single point, and 

 both writers give additional simple setse, which do not exist on our spe- 

 cies, but which, as figured by these authors, do not agree with each 

 other. The compound setse on our species do not seem to be bidentate, 

 but this may be owing to our object-glass not being sufficiently good. 

 Marion-Bobretzky also show a peculiar destitution of the margin of the 

 stem, near its end, not shown by Marentzeller, and not seen in our spe- 

 cies. 



STREPTOSYLLIS, n. g. 



AntennaB, three; tentacular cirri, four; dorsal cirri, partly smooth, 

 partly articulated ; oesophagus unarmed, with a circle of papillae at its 

 anterior end ; stomach passing directly into the intestines ; setae of two 

 kinds, simple and compound, both kinds covered by a membrane exter- 

 nally ; * palpi united for most of their length, turned downward so as 

 not to be visible from above. 



It will be seen that this genus agrees in some respects with Amblyo- 

 syllis Grube {Pterosyllis CLAPARiiDE), but the head is not " winged"; 

 the setae are very peculiar, and the dorsal cirri cannot be described either 

 as smooth or moniliform, since both forms occur on the same specimen. 

 It would, perhaps, be well to include the peculiar form of the setae in 

 the generic description. Unfortunately, we found but one species, and 

 it seems better not to multiply characteristics on such a narrow basis. 



Streptosyllts aren^, n. sp. 

 (PL. II, III, Figs. 17-23. ) 



Head convex, sides and front regularly rounded (fig. 17), posterior 

 margin curved forward, posterior angles bluntly rounded. Eyes, six ; 

 anterior pair small, crescentic, just behind and outside the origin of the 

 lateral antennae ; outer posterior pair largest, irregularly oval, in con- 

 tact with the inner pair, or sometimes merged with them; inner pos- 

 terior pairs small, circular. 



The antennae and tentacular cirri are never annulated, but are more 

 or less regularly wrinkled. They vary much in form. They may taper 

 quite regularly from base to apex, or only along their outer third or fourth, 

 or they may be somewhat clavate. The lateral antennae arise very close 

 to the anterior margin of the head ; they are from three to four times 

 as long as the head. The median antenna, longer than the lateral, arises 

 a little back of the eyes, near the posterior margin of the head. 



The buccal segment in alcoholic specimens, or in living contracted 

 specimens, is about one-half as long as the next segment, but in exten- 

 sion it may nearly equal the length of that segment. The upper ten- 

 tacular cirrus is a little longer than the lower cirrus, a little shorter than 

 the lateral antennae. 



Stem of compound setae terminating in four teeth or lobes. 



