no. 3610 ARCHIANNELIDS — KIRSTEUER 5 



furnished with six setae. The type of setae is also different in these 

 two species. In S. parvus the longest bristle is bifurcated and the 

 other five bristles on each parapodium have broad and blunt tips; in 

 S. archboldi the longest and hairlike seta has a round tip and the rest 

 of the setae are distally bifurcated. Saccocirrus maculatus is clearly 

 distinguished from S. archboldi by having only 26 segments and, 

 further, by being marked with black dots, which are irregularly 

 scattered over the greater part of the body surface but are so densely 

 arranged on the pygidium that it looks black. 



Genus Protodrilus Hatschek 



Protodrilus corderoi Marcus 



Protodrilus corderoi Marcus, 1948, pp. 5-7, figs. 11-16. 



The nine specimens that were collected on Dominica agree in most 

 details with the description given by Marcus (1948) for specimens 

 from Brazil. The living worms are greyish in color, semi transparent, 

 and attain a length up to 4 mm (in the Brazilian specimen, 6 mm) 

 and a maximum width of 0.1 mm. Up to 37 segments are found in 

 the present specimens. The head region is, under normal circum- 

 stances, only slightly wider than the rest of the body. In a squeezing 

 preparation, however, the cephalic area becomes broadened and 

 rounded in shape as was illustrated by Marcus (1948, pi. 3: fig. 11). 

 The tentacles extend over 280 /z and are irregularly beset with cilia. 

 Cilia are found also on the tip of the prostomium, on the lateral and 

 dorsal aspects of the body segments, and along the posterior border of 

 the anal lobes. The nuchal organs are small ciliated pits situated 

 posterior from the tentacles on the lateral sides of the head. There 

 are no eyes, statocysts, or transverse bands of cilia. 



The salivary glands extend posterior into the third segment in the 

 smallest animal and into the seventh segment in the longest one. 

 The two anal lobes have the same shape as was figured by Marcus 

 (1948, pi. 3: fig. 12). In only two animals small ovocyts were found 

 when studied alive. The other specimens were sexually immature. 



