THREE NEW SPECIES OF POLYCHAETOUS ANNELIDS 

 FROM CHESAPEAKE BAY 



By Aaron L. Treadwell 



Department of Zoology, Vassar College, Poughkeepsie, N. Y. 



Among the polychaetous annelids collected in 1920-21 in the course 

 of the biological survey of Chesapeake Bay, conducted by the United 

 States Bureau of Fisheries, were found three undescribed species : 

 Two representatives of the family Syllidae and one of the family 

 Spionidae. The types have been deposited in the United States 

 National Museum. 



Family SYLLIDAE 



PIONOSYLLIS MANGA, new species 



Figure 1 



The type is described from a female having a body width of 0.2 

 mm. and a total length of 2 mm. with 43 somites. The palps are 

 fused dorsally for only a short distance, but ventrally they appear 

 as two fleshy rounded lobes widely divergent from each other. The 

 prostomium is three lobed (fig. 1, a), with the anterior lobe smaller 

 than the lateral ones. Each anterior tentacle is attached just lateral 

 to the depression between the corresponding lateral lobe and the 

 anterior one and extends considerably beyond the palps. The median 

 tentacle is attached near the posterior border of the prostomium and 

 is long, slender, and of uniform width throughout. The lateral ones 

 have narrow bases and expand into one or two flask-shaped enlarge- 

 ments beyond this. In some cases these have an appearance as if 

 jointed (because of the constrictions between the enlargements), but 

 this is entirely superficial. There are three pairs of eyes, the anterior 

 ones very small and situated near the bases of the lateral tentacles, a 

 larger pair near the posterior border of the prostomium, and a still 

 larger pair a little anterior to these and near the lateral margin. 

 Only the ventral tentacular cirri are present, and they resemble the 

 lateral tentacles in form. The dorsal cirri also resemble the tentacu- 

 lar and are uniform in character throughout the body. The anal 

 cirri are slender and longer than any of the dorsal cirri (fig. 1, h). 



NO. 2867.— Proceedings U. S. National Museum, Vol. 79, Art. I. 



56789—31 1 



