Clare Inland Purvey — Archiannelida and Polychacta. 47 25 



Streptosyllis Webster and Benedict. 



This genus was created by Webster and Benedict (1884, p. 711), for 

 a species, 8. arenae, found at Provincetown, Mass. 



The same observers described a second species, S. varians (1887, p. 718), 

 from Eastport, Maine. The genus was defined in 1884, from observations 

 on only a single species, as follows : — 



"Antennae, 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 externally 

 (stem of compound setae terminating in four teeth or lobes) ; palpi united 

 for most of their length, turned downward so as not to be visible from 

 above." 



In 1895 de Saint-Joseph (p. 192) found a pelagic individual belonging to 

 this genus, and referred it to the 8. varians of Webster and Benedict. There 

 seems little doubt, however, that his specimen belongs to a distinct species 

 as it exhibits several notable distinctions, the chief being (1) the palps are 

 ventral, and invisible from the dorsal side, whereas those of S. varians are 

 exceptionally prominent, and project beyond the front of the head ; (2) capillary 

 setae commence on the 12th segment, in 8. varians on the 21st; (3) the 

 proboscis occupies segments 1-4, the proventriculus the 5th to the 8th 

 segments, whilst in S. varians, the proboscis occupies 6 segments, and the 

 proventriculus 8 segments. These differences are sufficient to justify the 

 creation of a new species for ihe French specimen ; but, as explained below 

 (p. 27), it may be identical with S. Websteri sp. n., to which it is evidently 

 closely allied. 



The large thick spines are present only in segments 1-5, in S. vanans 

 W. and B., in segments 1-23. ' 



It is now possible to define the genus Streptosyllis with greater accuracy: — 



Syllidae with palps fused at the base, filiform at the tip ; tentacular 

 cirri two pairs ; cirri smooth or very indistinctly moniliform ; pharynx 

 unarmed ; feet in a variable number of anterior segments with thicker 

 spines, shorter and thicker setae, with shorter terminal pieces, than in 

 the subsequent segments ; simple seta dorsally ; tips of the shafts of the 

 setae dividing into several teeth or lobes ; ventral cirri long in posterior 

 segments ; reproduction direct, with pelagic stage. 



1 I have examined the types of this species now in the U.S. National Museum and in Union 

 College. 



e.i.a. peoc, vol. xxxi. D 47 



