440 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 10 



pairs in the thorax. Abdominal hooks are unusual in that they lack a 

 hood and the crest has several rows of transverse teeth (pi. 57, fig. 4). 

 The proboscis is a voluminous sack that appears to be thin and epithelial 

 throughout. The pygidium lacks appendages. 



This genus remains known through a single species (see below) ; its 

 phylogenetic relations with other genera are doubtful since it departs 

 widely from other capitellid genera in several important respects. 



Protocapitella simplex Berkeley 

 Plate 57, Figs. 3, 4 



Berkeley, 1932, pp. 669-670, figs. 1-4. 



Collections.— U77-42 (1), 1491-42 (1), 1492-42 (1). 



Only 3 individuals are in the collections; one is complete and the 

 others are nearly so; they have large eggs in the body cavity hence are 

 perhaps nearly mature. Total length is only 20 mm as originally 

 described; the number of segments is 63; next to Capitita ambtseta (see 

 above) this is one of the smallest of known capitellids. The general 

 appearance is slender and cylindrical; it is translucent to pale (pre- 

 served ) . 



The prostomial lobe resembles that of a lumbrinerid more nearly than 

 that of a capitellid since it is broadly conical and not covered by the peris- 

 tomium ; the nuchal slits are inconspicuous at its posterior margin. There 

 are 4 eyes in trapezoidal arrangement in front of the nuchal slits. Each 

 consists of a minute, embedded dark speck; the anterior pair is slightly 

 larger and a little farther apart than the posterior pair. They may be 

 seen by slightly depressing the prostomial lobe. 



The peristomium is unusually prolonged as first described ; its surface 

 is smooth and it lacks parapodial parts. The proboscis is not everted in 

 any individual. By dissection it is seen to consist of a spacious, wrinkled 

 sack with epithelial walls. The thin-walled oesophagus seems to extend 

 through about 14 segments, thus marking the possible separation between 

 thorax and abdomen. 



The second (first setigerous) segment is complete with notopodial 

 fascicles and neuropodial uncinigerous ridges ; this arrangement continues 

 throughout the body. Notopodia are dorsolateral to lateral in position; 

 the 2 of a pair are widely separated from each other middorsally. Neuro- 

 podia are lateral to ventrolateral in position and only a short distance 

 from their respective notopodia. No lateral organs have been dis- 

 tinguished on any segments. 



