132 PROCEEDINGS OF THE NATIONAL MUSEUM vol.84 



carinellum with the seventh legs 8-jointed, but the other males in 

 both species have these legs 7- jointed. 



Males with a comb of fine hairs beneath the last joint of the first 

 three pairs of legs; none of the ensuing legs with velutinous pads 

 such as are found in some species of Colactis. Females with combs 

 of hairs beneath the first two pairs of legs. 



Males with the first tln-ee pairs of legs 7-jointed and also oc- 

 casionally the seventh pair, the other legs distinctly 8-jointed. Fe- 

 males with only the first two x)airs of legs 7- jointed, the other legs 

 8-jointed. 



HEPTIUM CARINELLUM, new species 

 FiGXJRES 18, f-j; Plate 4, Figxjees 3, 4 



Body long and very slender, loose jointed, the anterior subseg- 

 ments greatly exposed in all specimens, dorsum distinctly depressed 

 in both sexes; length 25 to 38 mm, width 1.4 to 1.7 mm; number 

 of segments 61 to 70 (pi. 4, figs. 3, 4). 



Eye cluster definitely triangular, with 29 to 46 ocelli usually in 

 6 rows but sometimes in 7 rows; sense organ the size of an ocellus 

 and close to the third and fourth rows of ocelli. 



First segment with 10 prominent crests, the inner ones extending 

 almost halfway to the front margin; the third and fourth crests, 

 counting outward from the center of the dorsum, longer than the 

 others; surface in front of the crests not tuberculate; setae in a 

 triarcuate series. 



Second segment with the dorsal crests quite thick and strongly 

 elevated, but on the ensuing segments the crests gradually decrease 

 in size and height, and behind the front third of the body they are 

 lower and slenderer than in any of the other American species exam- 

 ined. The secondary crests, although obsolete on the first five seg- 

 ments, are more conspicuous on the segments immediately following 

 than farther back, and are scarcely visible on the last few segments. 



Transition to the full number of dorsal crests occurs on segment 19. 



Primary crests with the apex almost a straight line when viewed 

 from the side; on each side immediately below the apex is a single 

 series of small, closely placed, circular pits; the lower sides of the 

 primary crests, all the secondary crests, and the rest of the dorsal 

 surface rather coarsely and irregularly reticulated. Behind the 

 secondary crests the surface of the segments faintly descends to a 

 slightly lower level. 



Poriferous carinae prominent; in outline slightly irregular, Avith 

 a broadly rounded anterior corner and an abrupt, nearly right- 

 angled posterior corner (fig. 18, /). On the midbody segments the 



