1921.] Fauna of the Chilka Lake : Polychaeta. 603 



to Dendronereis. The obvious distinction that the branchiae of Dendronereis are 

 formed by modification of th e dorsal cirrus, whilst those of Dendronereides lie beneath 

 and do not involve the dorsal cirrus, is not so decisive as it appears at first. I have 

 shown above that the branchiae of Dendronereis are attached to the base of the dorsal 

 cirrus, the latter structure remaining unchanged, at the tip of the swollen base. If 

 figs. 6e, 6h, are examined, it will be seen that the branchiae of Dendronereides also 

 are attached to the base of the dorsal cirrus, though in this case the base is not 

 elongate, and the area of attachment is condensed. A more important distinction 

 between the two genera lies in the fact that the branchiae of Dendronereis are sup- 

 plied with an elaborate system of blood-vessels, whilst those of Dendronereides are 

 apparently not. In both genera the gills are concentrated on the anterior part of the 

 body. These resemblances, however, may be due to convergence. It is remarkable, 

 however, that in both genera there is great simplification of the foot behind the bran- 

 chial region, and an unusually large number of foot-lobes in the anterior segments. 

 In both genera the proboscis is provided with soft papillae, and devoid of horny 

 paragnaths. In both genera also, heterogomph setae are absent, and a number of 

 the spinose setae have very long slender teeth. 



This genus also shows rather more distant affinities with Tylonereis, Cerato- 

 cephala, and Tylorrhynchus, 



Dendronereides heteropoda, sp. nov. 

 (Plate XXI, figs. 6a — n, and text-figs, loa-f.) 



Nine specimens of this species are available. They are all immature, with new 

 segments in process of formation in the posterior region. The type specimen is 

 66 mm. long, and consists of 140 segments. The body is long and slender, and 

 attains its greatest width at the 8th setigerous segment. Dorsally the anterior 

 margin of each segment is distinctly concave. The anterior segments are two or 

 three times as wide as long. Further back, the length of the segments increases till 

 it exceeds the width, but in the posterior region the segments become short again. 



The anal segment is large and button- shaped, and the anus is terminal. The 

 two short anal cirri are ventro-lateral in position, and taper to filiform tips. 



The head, palps, tentacular cirri, and anterior dorsal region of the body are 

 rusty red in colour, the pigment being most marked on the head. In some of the 

 specimens the colour is quite gone, except for the three dark patches on the head. 



The head (fig. 6a) is relatively very small, and the width greatly exceeds the 

 length. In front it is deeply bilobed, with the small tentacles at the tips of the 

 lobes. The eyes are rather small in the specimen figured, and are larger in other 

 individuals. They are placed near the postero-lateral angles of the head, and the 

 anterior pair are more widely separated than the posterior pair. The palps are 

 short, stout, and contracted. At the back of the head, in the median dorsal line, 

 is a narrow transverse band of deep reddish brown pigment. At the base of each 

 tentacle there is a more diffuse patch of the same colour. The bases of the palps, 



