236 Records of the Indian Museum. [VGE Vs 
Nais pectinata, sp. nov. 
The greater number of specimens belong to this species ; they 
are those which were at first separated from the rest by the 
obvious forking of the dorsal needles. 
On examination with the oil immersion lens, however, I was 
surprised to find that these setae had an entirely different form 
from what I had supposed. Instead of being simply forked, they 
were in all cases ctenate, the two prongs at the sides being the 
strongest, and the interval between them being filled in by a 
number of extremely fine points, two, three, four, or five in 
number. It was these intermediate points which had not been 
detected with the ordinary high power (Zeiss DD, oc. 6); with this 
degree of magnification the outermost prongs are alone visible, 
and hence the setae appear to be bifurcate at their extremity. It 
is not always possible to count accurately the intermediate prongs 
even with ;5 in. oil immersion and compens. oc. 6, and recourse to 
a I2 oc. is sometimes necessary. 
Such a form of dorsal needle has not hitherto been described 
in the genus; so far as I know, indeed, this type of seta has not 
previously been met with in the family, and the nearest approach 
would seem to be the fan-shaped dorsal needles of Dero tonkinensts, 
Vejd. It would therefore appear to be a character of quite 
sufficient importance to justify the erection of a new species. 
The description of the animal is as follows :— 
Length of single individual (preserved specimen) about 2 mm. 
Prostomium well marked, conical with rounded tip. No eyes. 
Segments 27—31. 
The buccal cavity, in segment ii, is narrow and tubular; the 
pharynx, which succeeds it, extends from segment iii to iv. 
The cerebral ganglion appears to be deeply bifid both in front 
and behind ; it is broader from side to side anteriorly than pos- 
teriorly. 
The ventral setae are of the usual type, and are differentiated 
into two groups, those of segments ii—v, and those posterior to 
these. 
Those of segments ii—v are regularly 3 per bundle, are about 
56 » in length, and have a markedly thinner shaft, with its 
proximal portion less strongly curved than those of the posterior 
segments. The distal prong is 1} times as long as the proximal, 
but this latter is the thicker,—1} to twice as thick as the former 
at its base; both prongs are slightly swollen near their bases. 
The nodulus is proximal to the middle of the shaft, the relations of 
the distal and proximal portions of the shaft being 4 : 3; the 
swelling of the nodulus is equal on both sides of the shaft 
(fig. Ia). 
The posterior ventral setae are sometimes 2, often 3, not un- 
frequently 4, and occasionally 5 per bundle. In length they are 
51I—56 m, the latter, longer measurement being that of setae 
towards the hinder end of the body. The shaft is thicker, and its 
