HETEROCLYMENE ROBUSTA. 335 



The separate segment (fragment) lias bristles and hooks. The latter have 

 moderately long, curved shafts, increasing in diameter from the base to the shoulder, 

 then narrowing at the neck, which increases in breadth distally, and with a somewhat 

 high crown on which are six teeth behind the great fang, which makes less than a 

 right angle with the neck, and a curved gap (concavity) with a slight eminence exists 

 between it and the origin of the gular bristles, much less, however, than in the hook of 

 Isocirrus D. 



The bristles are strong and straight, with tapered tips and narrow wings. Beyond 

 the wings in some is a flattened region ending in the delicately tapered tip. The more 

 slender forms do not show traces of wings. 



Genus CXXV.— -Heteroolymene, Amvidsson, 1906. 



Nuchal organ rather long. Distinct cephalic rim. Proboscis with flat papillae. 

 Behind the mouth are two lateral glandular areas. The feet of the eighth segment in the 

 middle. Distinct, naked segments posteriorly, the last being short and overlapping the 

 anal rim. The ventral cirrus of the rim is longest, the others are somewhat long. Anal 

 cone distinct, with the anus prominent. Cephalic plate with distinct glands. The anterior 

 segments with evident glandular bands. The hook-like bristles of segments 1 to 3 are 

 powerful, and develop gular bristles under the main fang in the succeeding segments. The 

 anterior bristles are winged, and have spinous tips. The posterior bristles have smooth 

 tips. Tube free and straight ; somewhat thin. 



1. Heteroolymene robusta, Amvidsson, 1906. Plate C, fig. 23— tail; Plate CIX, fig. 



4 and 4 a — bristle and hook. 



Specific Characters. — The anterior process of the head somewhat small. The cephalic 

 border with lateral notches, and a median one posteriorly. No eyes. Body with nineteen 

 bristled and five terminal unarmed segments ; the last being short, and sometimes the 

 fourth also. The anal rim has between the longer cirri a series of shorter ones, but the 

 mid- ventral is longest. Nephridia in segments 7 to 9. Anterior segments 1 to 9 with 

 anterior glandular bands, and the third and fourth have glandular areas behind the feet. 

 In the ninth bristled segment the band is both dorsal and ventral, a triangular area 

 passing in front over the eighth. 



Hook-like bristles of segments 1 to 3 short, thick, and somewhat tapered at the ends. 

 The typical hooks with eight to nine teeth. Both kinds of bristles have long points, are 

 best developed in segments 9 to 16, and their basis is prominent. Colour : Third bristled 

 segment with faint red specks behind the feet, the next has specks on the feet and on the 

 anterior region. The fifth, also has specks on the feet, segments 6 and 7 have none, 

 and the latter is brownish-yellow posteriorly. The reddish coloration is marked. In one 

 example the cirri and rings near the anus were reddish-brown. 



