102 BULLETIN 60; UNITED STATES NATIONAL MUSEUM. 



small spines. The lower half is closel}^ spinose. There is a large 

 hairy area at the lower angle, and a small one on the upper border. 



The first cirri have very unequal branches, of 14 and 29 segments, 

 respectively. They are densely armed with whorls of slender spines. 

 The rest of the cirri are very long and slender, with spines on the 

 anterior side, two or three in each group being large. Distally there 

 are groups of small spines on the posterior side also. The general 

 arrangement of these spines conforms to that described in //. rex. 

 The rami are subequal in cirri ii, iii, and iv, but in v and vi the 

 endopod is greatly reduced, about half as long as the exopod, very 

 slender, and composed of 28 segments in the fifth cirrus (Plate V, 

 fig. 13), 25 in the sixth. 



The terminal apj)endage (Plate V, fig. 12) is nearl}^ 4 mm. long, about 



one-seventh' the length of the sixth cirrus, 

 composed of eight or nine segments, and 

 without bristles. 



The long penis is closely annulate, acu- 

 minate at the distal end, where it bears a 

 minute pencil of delicate hairs. 



This species is related to Iletendepas 

 indica (Gruvel) described from Singapore, 

 and H. gigas Annandale, which have the 

 peduncle similarly lengthened. In all 

 other known forms the peduncle is very 

 much shorter. H. indica diflers from 

 77. cygnus by its much compressed capitu- 

 lum, not distinctly separated from the 

 comparatively wider peduncle; bv its 

 FIG. 35.-HETERALEP..S cYGNTjs, NAT- ^^^^ chcstnut, slightly vinous color, the 



ITRAL SIZE. •> t^ J 5 



smoother cuticle of the capitulum, which 

 has a few small tactile bristles {'''' soles sensitives''^), and by the different 

 arrangement of spines on the cirri. The terminal appendage in H. 

 indica has twelve segments, the last four bearing bristles, and ter- 

 minating in a bunch of bristles, whilst in IT. cygnus there are but 

 eight or nine segments, none of them setose. The mandible in 

 77. cygnus has more slender teeth, with a fringe of bristles on the 

 lower margin, wanting in II. indica; and the penis is more conspicu- 

 ously and closely annulated. 



Iletercdejxis gigas {A.TLX\2iX\dia\&)^'^ is a larger species than H. cygnus^ 

 with the peduncle similarly lengthened. It has "short, stout hairs 

 scattered singly " on the capitulum, and large, feebl}' differentiated 

 scuta, thereby differing from 77. cygnus. 



c Alepas gigas Annandale, Mem. Asiatic Soc. of Bengal, I, 1905, p. 80. Bali 

 Straits, 160 fathoms. 



