Records of the Indian Museum. [VOL VaLI. 
No 
No 
oO 
In the specimens in which the gills were best developed they 
were, in the most anterior segments, about ‘54 mm. in length; 
but exact measurements are difficult, owing to their being some- 
what curled and twisted ; in the next succeeding segments, where 
they are longest, they were ‘72 mm. long, or about 2—24 times 
the diameter of the body in this region. In other specimens 
they were frequently not so long,-—about ‘27 mm., or equal to the 
diameter of the body. 
Some idea of the progressive diminution in size may be 
obtained from the following data :—in an animal of 130 segments, 
the gills at the 4oth segment were small finger-like lobes, at the 
50th large tubercles, at the 60th small tubercles, and beyond this 
absent. In another specimen of 130 segments, they disappeared 
at the 76th segment; in one of 87 segments, at the 67th; they 
were present, as tubercles only, on the 73rd and 56th segments 
of two animals whose posterior ends had been destroyed at these 
levels respectively; and in another specimen they were quite 
small finger-like lobes on the 17th, and disappeared altogether 
beyond the 24th segment. Behind the region of the gills, in these 
preserved specimens, the series is continued as a pushing out of 
the body-wall, which is raised round the base of the dorsal setal 
bundles into small pointed conical elevations ; but these are merely 
such as would be produced by a contraction of the muscles of the 
setal sac pushing out the bundles of setae, and indeed may have 
been so produced at the moment of fixation. 
Pigmentation.-- As in the related forms the anterior end 
of the body is markedly pigmented (pl. xi, figs. 1,2, 3). The pig- 
ment occurs as irregular blotches on the prostomium and pre- 
branchial region; behind this it has a fairly definite segmental 
arrangement, as irregular bands extending over the dorsal and 
lateral surfaces, but leaving the ventral surface free ; the bands are 
formed of a number of irregular spots or blotches, which may or 
may not be confluent. The pigment may be very slight in amount 
and scattered in its distribution ; in any case it fades away after 
the first few segments, e.g., beyond the 8th, 12th, or 13th. 
Pigment also usuaily, but not always, occurs on the gills,—not 
all over them, but in streaks along their lateral aspects (pl. x1, 
fig. 1). The pigmentation of the gills corresponds roughly, as 
regards number of segments, to that of the body. 
The pigment appears to be located in peritoneal cells lining 
the body-wall, and to be of the same nature as that of the 
chloragogen cells; similar cells invest the dorsal vessel as far 
forward as thesecond gill, and sometimes some of the lateral loops 
also [v. inf., and cf. Bourne (4), and his fig. 3]. 
Setae.—The dorsal setal bundles begin with the gills; the 
setae are of two kinds, long and short. The long (‘capillary ’) are 
straight, smooth, tapering gradually to a very fine point, and, 
where they are free from the gills and can be measured, in length 
commonly about 330 ». The shorter (‘needle’) setae have 
typically the form shown in fig. 1; the distal curve and the 
