1921.] Fauna of the Chilka Lake : Polychaeta. 585 



The largest specimen is 92 mm. long, and has 81 setigerous segments. Others 

 are 65, 56 and 44 mm. in length, with 84, 66 and 81 segments. 



The dorsum is deeply coloured with purplish brown pigment, dark in front, and 

 growing paler behind. The ventral surface is colourless. The head (figs. 8a, 8b) is 

 deeply coloured, with a median pale streak which broadens out between the eyes. 

 The palps are more faintly coloured. The basal part of the proboscis is tinged with 

 the purple pigment. The bases only of the tentacular cirri are deeply coloured. The 

 first few segments have the dorsum pigmented all over, except for a few pale oblique 

 lateral grooves. Further behind, the pigment forms a definite pattern on each seg- 

 ment (fig. 8d). The central part becomes paler, leaving a dark band on each side, 

 separated from the central part by a narrow pale band. The intersegmental areas 

 are pale. In the anterior segments the base of each foot is pigmented, but in the 

 middle and posterior regions the feet are colourless. The pigment is not uniformly 

 diffused, but is more or less granular, especially in the dark lateral bands. 



The head (fig. 8a) is considerably narrower in front than it is behind, and the 

 length is about equal to the greatest width. It projects a little in front between the 

 tentacles, which are |rd to jth as long as the head. In small specimens the palps are 

 separated from the head by grooves, but in large specimens these grooves become 

 indistinct. The palps are large and stout. The eyes, in immature individuals, are 

 small and dark, equal in size, the anterior pair being a little further apart than 

 the posterior pair. The tentacular cirri have dark ringed ceratophores. The pos- 

 terior dorsal pair are much longer than the others, reaching back usually to the mid- 

 dle of the 6th setigerous segment, in some cases to the 8th and even the 12th seg- 

 ment. The anterior dorsal tentacular cirri are one-half to two-thirds as long. The 

 ventral cirri are approximately equal in length, being half the length of the ist 

 dorsal cirri. These sizes and proportions are subject to great variations. 



The paragnaths have the normal form and arrangement for the subgenus. Those 

 on the basal ring are longer than those on the maxillary ring. They are arranged as 

 follows : — 



Group I, 6-10, usually 7 or 8. Group V, absent. 



„ II, 18-20. 



„ III, 26-34, usually 28. 



„ ' IV, 35-41, varying greatly. 



VI, 3-5 usually 4, larger than the 



others, in a curved row. 

 VII and VIII, forming a continuous 

 band in two rows. 



The paragnaths of the anterior row in Groups VII and VIII are large ; those 

 forming the posterior row are more numerous and of different sizes. 



The jaws are of the usual shape, with eight teeth. 



The peristomium (fig. 8b) is nearly twice as broad as the succeeding segments. 

 In fig. 8a it is crushed by the extruded proboscis. 



The feet were examined in a specimen 56 mm. long, having 66 setigerous seg- 

 ments. 



The feet increase in size up to the 6th or 7th. 



