476 PROCEEDINGS OF THE ACADEMY OF [June, 



on XII and XIII the plates are continued by an indistinct, much 

 wrinkled and subdivided glandular area, while anteriorly both IV and 

 III are glandularly thickened on the ventral surface. On the first 

 10 or 11 somites a smooth rounded glandular (?) elevation occurs on 

 each side just dorsad and mediad of the notopodial tubercle; on the 

 anterior postbranchial somites these tubercles run together into a low 

 longitudinal ridge. Anus terminal, large. 



There are 3 pairs of branchiae on II, III and I\^, the first somewhat 

 the largest, and the third slightly the smallest, all beautifully arbores- 

 cent, with about 6 main branches from a central stem, and numerous 

 and fine subdivisions with a somewhat spiral arrangement, resulting 

 in a rather acute conical form, which in life must be very beautiful and 

 conspicuous. 



The third somite bears a dorsal setigerous tubercle only on its dorso- 

 lateral angles; the next 16 have dorsal setigerous tubercles and ventral 

 uncigerous tori. The latter are at first high up, but gradually assume a 

 more ventral position, until the last 9 are almost entirely on the ventral 

 surface, and the last 7 or 8 are separated by a median interspace not 

 exceeding their own transverse extent, which increases from before 

 caudad. 



Slender setse in a dense tuft, arranged more or less in the form of 

 an arc or horseshoe open ventrally or anteriorly. They are of two 

 kinds: simple colorless capillary setse, not especially slender, and glis- 

 tening straw-colored lance-shaped setae, with strongly fibrillated shaft, 

 and the end broadly margined on one side, narrowly on the other, both 

 flanges reaching nearly to the tapering pointed tip, and marked with 

 oblique fibrillse, which sometimes wear into a slight fringe, especially 

 on the broader margin. 



On somites IV to XIX the uncini are arranged in 2 rows, opposite 

 and facing each other, when retracted, in a groove ; on the abdominal 

 segments they form a single short row facing the head on the extreme 

 end of the uncigerous process. Their nmiiber is very great in the pos- 

 terior thoracic segments, the posterior row on XIX containing 260 

 and the anterior row evidently a considerably greater number. As 

 in other species of the genus the uncini are broad, flat pectinate plates, 

 the thoracic ones very constantly bearing 5 long sharp curved pro- 

 cesses, with a rudimentary apical 6th, and a minute tooth between the 

 first spine and the anterior muscular process of the base ; the abdominal 

 uncini have the 6th process usually well developed and the muscular 

 processes more pronounced. 



Suruga Bay, 3,723, 13-16 fms., type only. 



