652 A. E. Verrill — Tarhellaria, Nemertina^ and 



side rounded and the back flat and nearly concealed by the prom- 

 inent cirri and branchire. Anterior segments near the head rapidly 

 decrease in breadth. Head small, flattened, widest near tlie front 

 end, which is truncate or slightly emarginate; sides rounded. Two 

 small blackish spots, like imperfect ocelli, are situated near its pos- 

 terior border. 



The branchise begin on the 6th setigerous segment, rapidly be- 

 come of full size, when they are elongated, tapered, acute ligulae, as 

 long as the dorsal cirrus, but not quite so broad proximally. They 

 continue nearly or quite to the end of the body. 



The first two or three parapodia are quite small, but they rapidly 

 increase to about the 10th. The lower division consists, on the 

 anterior segments, of a torus filled with a crowded group of capillary 

 setae ; and a foliaceous lobe, prolonged above into a small papilliform 

 cirrus. The tori increase rapidly to the 10th segment and continue 

 of about full size to abo;it the 20th and then rapidly decrease to the 

 25th, when they become very small, and beyond this, at about the 

 30th, they are replaced by a papilliform lobe and a cluster of longer 

 capillary seta and 4 or 5 larger spiniform ones. 



The upper parapodium, anteriorly, consists of a broad flat lobe, 

 prolonged at the dorsal angle into a small acuminate cirrus; at 

 about the 25th-30th segment they change rapidly to a longer and 

 narrower falcate cirrus, with a constricted base, above which they 

 rapidly expand, on the outside, to a broad flat portion, beyond 

 which they taper gradually to the subacute tip; they are concave on 

 the dorsal side and are recurved over the back, like the branchial 

 cirri, which they equal in length. These cirri, at about the 35th 

 segment, are more than three times as long as broad, and about 

 twice as long as the ovate ventral lobe, though not much wider. 



The numerous crowded setre of the anterior ventral toriform lobes 

 are much alike, in the form of short, acute capillary sette, with 

 rather stout shafts. The capillary setse of the upper fascicle are 

 much longer and far more slender. 



On a parapodium from the 3 2d segment there are 12-16 long, very 

 slender capillary setae, with attenuated tips, as long as the dorsal 

 cirrus, and about 4 moderately large, straight, acute spiniform setae, 

 not half as long; in the lower fascicle there are about 18 shorter 

 capillary setae of the same kind, rather longer than the ventral lobe, 

 and three slightly bent spiniform sett^. 



On the posterior segments the seta3 are similar, but fewer, about 

 10 to 12 long ones in the upper fascicle, and 6 to 8 in the lower, with 



