644 Memoirs of the Indian Museum. [Vol. V, 



smooth part, and an expanded posterior part, the latter bearing the swollen tori. 

 The dorsal tori (fig. 24c) are widely separated in segments 2-4, and then gradually 

 approach each other, till from the 12th segment backwards the tumid lips of the tori 

 form a dorsal ridge. 



The sculpturing of the integument of this species is very characteristic. On the 

 ventral surface (fig. 24A) there is, in the median line of segments 2-5, a row of hexa- 

 gonal areas, 2 or 3 in each segment. These are replaced in segments 6-12 by raised 

 areas not clearly marked off except by a median transverse groove. In segments 

 5-12, on each side of the raised median areas, are narrow hexagonal areas, the outer 

 ends of which reach to the ventral setae. In side view (fig. 24B) the lateral organs 

 are clearly shown in segments 5-12, less clearly in segments 2-4, and are very in- 

 distinct on the abdominal segments. Dorsally (fig. 24c) there are median hexagonal 

 areas on segments 6-1 1. A shallow lateral groove runs backwards on each side from 

 the 13th segment, but occasionally it begins near the anterior end. It is probably 

 due to the contraction of the specimens, and the presence of very powerful longitudi- 

 nal latero- ventral bands of muscle. 



The branchiae commence between the 55th and 60th segments. They lie under 

 the dorsal parapodial lobes (figs. 24D-E). The anterior branchiae consist of 3 or 4 

 short rounded lobes, hidden by the parapodial lobes. Towards the tail the bran- 

 chiae increase in number and length. The largest, near the posterior end, have 

 9-1 1 finger-shaped lobes, attached to the underside of the dorsal parapodial lobes 

 (fig. 24E). The latter structures are part of a thin membrane which surrounds the 

 segment like a collar, the anterior margin being fixed, the posterior one free and pro- 

 duced into four rounded lobes, the two larger carrying the dorsal setae, the two 

 lateral, which are not so pronounced, carrying the ventral setae. The collar is 

 attached to the body-wall near the middle or the beginning of the posterior third of 

 the segment. The appearance of this part of the body is very like that of Heteromas- 

 tus. 



In segments 2-7 the dorsal and ventral tori contain only capillary setae. They 

 have narrow wings (fig. 24F), and taper to a slender tip. The bundles of the 2nd 

 segment (ist setigerous) have about 16 setae in each, the 3rd~7th segments have 

 20-40 setae in each bundle. In segments 8-12 the bundles contain only long 

 crochets (fig. 24G), which closely resemble the similar setae of Heteromastus. The tip 

 (fig. 24H), which is enclosed in a long narrow sheath, is not expanded as in Hetero- 

 mastus. It terminates in a strong tooth, with 5 or 6 slender spines on the crest. 

 There is a very slight nodulus where the seta pierces the skin. The nodulus lies just 

 within the proximal half of the seta. Each bundle contains 20-40 of these setae. 



The transition between the thoracic crochets and the typical abdominal crochets 

 is not so abrupt as in other species of the family. The typical abdominal crochets 

 are much smaller than those of the thorax (fig. 24K), they have a more distinct 

 swelling below the neck, the sheath over the tip is relatively shorter, and the nodu- 

 lus is more distinct, and is in the distal half of the seta. On the anterior abdominal 

 segments, the setae (fig. 24J) are intermediate in size, rather more like the thoracic 



