TWO NEW SPECIES OF POLYCHAETOUS ANNELIDS FROM 

 THE ARGENTINE COAST 



By A. L. Treadwell 



0/ Vassar College, Poughkeepsie, N. Y. 



Through the kind offices of the United States National Museum I 

 have been enabled to study the annelids of the collections made by 

 the well-known Uruguayan naturalist, Dr. Florentino Felippone, of 

 Montevideo. In the material last sent me there are two new species 

 described as Halosydna grisea and Leodice argentinensis . The types 

 are in the collections of the National Museum. 



HALOSYDNA GRISEA, new species 



The type (Cat. No. 19279, U.S.N. M.) (Felippone No. 3250), from 

 the " coast of Argentina," is 40.5 mm. long; the greatest body width, 

 measured to the margin of the elytron on either side, is 5 mm. 

 The prostomium is 1 mm. wide, its length about equal to its width. 

 The anterior margin of the prostomium is prolonged on either side 

 into the cirrophore of the lateral tentacle, which is about half as long 

 as the prostomium. (Fig. 1.) In the type the partially protruded 

 pharynx pushes the prostomium dorsally so that the posterior margin 

 is straight instead of notched and the narrowing at the base of each 

 lateral cirrophore is not clearly seen. The anterior median groove is 

 well marked and its postero-dorsal continuation divides the prosto- 

 mium into hemispheres. The anterior eyes are larger than the pos- 

 terior and are situated at the point of greatest width of the 

 prostomium. Both pairs have lenses; the anterior one faces dorsally, 

 the posterior one laterally. The prostomium (in preserved material) 

 is colorless, the cirrophores and basal portions of the tentacles colored 

 brown, with an uncolored portion at the cirrophore apex. 



The tentacles are all rather slender, pigmented only toward their 

 bases, of uniform diameter to the end, but terminating in a fine point. 

 The style of the median tentacle is about as long as the prostomium 

 and median cirrophore taken together. The styles of the lateral 

 tentacles are more slender than the median and extend to about one- 

 half its length. In the type only one palp remains, and this is badly 

 broken. In another specimen the basal portion of the palp is one- 

 half the width, and its total length fully five times the length of the 



No. 2797.-PROCEEDINGS U. S. NATIONAL MUSEUM, VOL. 75, ART. 26 

 41197—29 1 



