igoy.] Records of the Indian Mtiseiim. 135 



parts each bearing four pairs of bundles, the four posterior segments 

 of the anterior part of the body being also separated by a distinct 

 constriction from those in front {c) ; finally, in a specimen where a 

 deep constriction divided off an anterior portion of eleven body- 

 segments from a posterior of eight chsetigerous segments, the new 

 prostomium, mouth, buccal cavity and cerebral ganglion of the 

 posterior half could be distinctly seen {v. plate v, fig. 4). The 

 regions of the alimentary canal which I have called '^ crop," and 

 '' stomach " are, however, differentiated in the posterior half of the 

 dividing worm at an earlier stage than this. It may be noted here 

 that the seat of the constrictions, secondary as well as primary, is 

 always marked in addition by a conspicuous extension laterally of 

 the nervous matter of the ventral chain ; these lateral extensions 

 spread so far as almost to meet dorsally, and this takes place on the 

 anterior as well as on the posterior side of the actual site of con- 

 striction (y. plate v, fig. 5). 



Figure 6 represents the site of constriction in one of the speci- 

 mens examined. The anterior setal bundles of the posterior worm 

 are seen to be developing ; they thus arise as new formations, and 

 from the first point forwards, not perpendicularly outwards. If the 

 groups of setae already existing posterior to these (originally the first 

 pair behind the constriction) persist as the setae of the sixth segment 

 of the second worm, then each act of fission involves the intercalation 

 of five newly formed body-segments behind the site of constriction. 

 The same figure shows also a group of developing setse immediately 

 in front of the constriction ; new segments are therefore formed on 

 both sides of the site of constriction. 



Alimentary system. — The mouth is ventral, and leads into a 

 buccal cavity of small extent. This is succeeded by the pharynx, 

 a thick- walled tube, which extends backwards as far as the septum 

 between the second and third segments, and is attached to the 

 body-wall by numerous fine, short, sometimes Y-shaped muscular 

 fibres. The oesophagus occupies the third segment, it is narrower 

 behind than in front, and is usually short, about half as long as the 

 pharynx ; in the specimen mentioned previously as being perhaps 

 pathological, it was of a length about equal to that of the pharynx. 

 The crop, which follows, is a dilated portion of the canal, occupying 

 a little more than three segments, the fourth, fifth and sixth, its 

 posterior end being in the seventh segment ; its walls are clear, and 

 one cell in thickness ; the degree of its distension varies ; it may 

 be ballooned so as to occupy the whole of the body-cavity in its 

 own segments. 



A well-marked and constant constriction separates the crop 

 from a second dilated region of the alimentary tract, which is dis- 

 tinguished by being sHghtly pigmented, of a hght yellowish-brown 

 colour, and by containing a large number of refractile globules like 

 minute drops of oil in its walls. It is situated in the seventh and 

 eighth segments. The intestine occupies the remainder of the body ; 

 its diameter is less than that of the stomach but varies somewhat ; 

 the anus is terminal. 



