222 Records of the Indian Museum. [Vou: Vig 
110 to 139 » (proximal to nodulus : distal to nodulus : : 61 : 49, 
or 82: 57). The other or * anterior ’ type is slenderer throughout, 
the prongs, especially the distal prong, also longer and slenderer ; 
the distal prong is 14 times as long as the proximal, while the 
Fic. 2.—Byvanchiodrilus menont ; setae of the posterior ventral IAGOS 38 HG 
nodulus is at the middle of the shaft or somewhat proximal 
(fig. 3). In length they measure I00 to 116 » (proximal to nodulus : 
distal to nodulus : :°57 : 57, ot 55 : 61). In both types) the 
distal prong‘is only about half as thick at its base as the proximal. 
The ‘ anterior’ type occurs on a comparatively small number 
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Fic. 3.—Branchiodrilus menoni: setae of the anterior ventral type; x 375. 
of the anterior segments of the body, the posterior type on the 
remainder ; but there is no defined limit to their distribution. 
Thus well-marked ‘ anterior’ setae may be found on segment xiv, 
and even behind this; or nearly all the ventral setae in the body 
may be of the ‘ posterior’ type. The change from ‘anterior’ 
to ‘ posterior’ is in any case not a sudden one, and may apparently 
