266 



Annelida Clicetopoda 



illary setse of the anterior segments (f. 150), evidently 

 agree better with Laoxome than with Potamilla. The 

 ordinary form of capillary setae on the posterior segments 

 is shown in f. 153, but there are a few with narrower mar- 

 gins, and also some with a single margin, similar to f. 149. 

 Body of nearly uniform size, a few of the last segments 

 tapering slightly. 



This species lives in tortuous galleries excavated in 

 compact shells, lined with a delicate membrane, which 

 projects from 6 to 10™°. l^o entire specimen was obtained. 

 They could not be withdrawn without breaking, and it 

 was difficult to follow the galleries, owing to their tortuous 

 course and to the compactness of the shells. 



A nearly entire specimen, having 100 segments, was 

 15°^ in length; width not quite 1°""^. ' Color, reddish-brown • 

 above, white below. 



This species lives in colonies, and scattered among 

 them were frequently found individuals with only three 

 pairs of branchise, light red, without eyes, quite short and 

 narrow. As in all other respects they agree perfectly with 

 the species described above, they may be the young of 

 that form. 



I have referred this species to Potamilla Mgrn., although 

 it does not agree with that genus in all respects. The 

 ventral sulcus is certainly continued on the dorsum. The 

 form of the shorter capillary setae has been already referred 

 to. Aside from these points it agrees with Potamilla. 



Fam. SERPULID^. 

 HTDROIDES Gunnerus. 

 Htdroides diaxthus Verrill. 



Serpula dianthus Yerr. Invert. An. Yin. Sound, etc., p. 620. 

 Htdroides dianthus Verr. In Notes on the Nat. Hist, of Fort Macon, N 



C, Coues and Yarrow (No. 5), in Proc. Acad. 



Nat. Sci. PMla., 1878 (advance sheets;. 



