482 THE ANNELIDA POLYCHAETA. 



prostomium in a tooth longer, stouter and more obtuse than the others, with the 

 plate extending cephalad of this tooth; teeth progressively reduced in uncini 

 towards ends of rows. Abdominal setae of anterior and median regions stout, 

 moderately curved, acute spines; those of the more caudal somites very fine, 

 long, curved distally where hmbate, with tips entire. 



Genotype. — P. takemoana, sp. nov. 



The general relationships of this genus are indicated in the key. In the 

 general character of its thoracic setae it suggests Vermiha, but differs decidedly 

 in its very characteristic abdominal setae, which are in no part geniculate or 

 denticulate, and also very obviously in the form of the operculum. Ditrupa 

 has the abdominal setae capillary and ahke on all the somites. 



Paumotella takemoana, sp. nov. 

 Plate 78, fig. 1-5. 



The general color is brownish yellow, with the parapodial processes paler. 

 The thoracic collar is transparent. The branchiae yellow. Operculum yellow, 

 with the rim black. 



Thorax composed of seven setigerous somites. The abdomen is deeply 

 longitudinally furrowed above and is flattened dorsoventrally, especially at 

 the caudal end; at its anterior end is a region not distinctly segmented, followed 

 by about fifty-five short setigerous somites. The total length of the type is 

 about 18 mm., its coiled condition making precise measurement difficult. The 

 width across the anterior end of the abdomen is 1 mm.; the width across the 

 posterior end of the thorax abruptly greater, 2 mm.; while the width across 

 the anterior end, inclusive of the collar membrane, is 3 mm. 



Ventrally the collar is entire, projecting cephalad as a triangular flap. On 

 each side the membrane is deeply incised, the incision separating the ventral 

 flap from the dorsal division, which is continuous with the well-developed thoracic 

 membrane. The thoracic membrane is high anteriorly and narrows gradually 

 caudad to the end of the fifth somite, where it appears to discontinue abruptly. 



The branchiae on each side are fifteen, or very near that number. They 

 become strongly coiled distally. The radioles in the preserved condition are 

 irregularly transversely wrinkled; each when cleared and magnified shows a 

 segmentation. (Plate 78, fig. 5). The radioles bear a double series of long slen- 

 der pinnae from base to tip, these increasing in length distad. Each pinna bearsj 

 numerous long, hair-like or ciliary processes along its sides. (Plate 78, fig. 5). 



