A new polychaetous annelid of the genus Nereis from Brazil

Aaron L. Treadwell
1920 Proceedings of the United States National Museum  
The collection contained two entire specimens of adult females with eggs. The length was about 30 mm. with a peristomial width of B mm. The only trace of color in the alcoholic material was a brownish tint, forming a fairly uniform shading on the anterior region as far back as the fifth somite. Behind this the color is limited to a darker brown median band, which at somite 12 narrows and becomes very indistinct for the remainder of the body. In the preserved material the dorsal blood vessel
more » ... al blood vessel shows as a prominent narrow stripe. The prostomium ( fig. 1 ) is very slightly rounded anteriorly, the width at the anterior margin being practically equal to that just in front of the anterior eyes. A median longitudinal dorsal groove extends from the anterior margin to the level of the anterior pair of eyes. The entire lateral margin of the prostomium is fused with the inner face of the palp, though as far back as the anterior pair of eyes a faint groove marks the line of fusion. Behind this point the fusion is complete. The tentacles are separated at their bases by a distance equal to their diameter, and are relatively small, conical, with acute tips. The palps are very thick and fleshy, as broad as the peristomium, with a very small terminal joint. Toward the end a transverse groove simulates an articulation. The tentacular cirri are small, most of them not reaching the apex of the palp. The posterior dorsal one is the most slender, and extended in one specimen as far as the posterior border of somite 2, while in the other it was much shorter. This is evidently a variation due to the preservation. The other cirri are not more than a third as long as this, conical, with acute tips ( fig. 1 ). Tlie peristomium is longer than the prostomium, and shorter than the second and third somites combined, though longer than the second. Toward the posterior end of the body there is a gradual decrease in the diameter. There is one pair of long, slender anal cirri.
doi:10.5479/si.00963801.58-2347.467 fatcat:ohqfzhtdvbetfj5abjmgsomtte