IQ2I.1 Fauna of the Chilka Lake : Polychaeta. 601 



the median ligule. The setae lie above and in front, of the median ligule, to which 

 the edges of the setigerous fillet are attached. The ventral division consists of two 

 anterior lobes, almost surrounded by the fillet, three posterior lobes, the ventral 

 ligule beneath the setae, and the ventral cirrus. The coarsely serrate setae are few 

 in number. 



In the 16th foot one of the posterior ventral lobes has disappeared. The 17th 

 and 18th feet (fig. 4.H) are similar. The two posterior lobes of the ventral division 

 are flattened at the base, and the spine terminates in a small papilla. In the 19th and 

 20th feet (fig. 4J) the upper anterior lobe of the ventral division has a small papilla 

 beneath it, which disappears in the 21st foot. The posterior lobes are still more 

 foliate. In the 21st foot the lower posterior lobe is almost entirely fused with the 

 upper one. 



In the 22nd foot (text-fig. gg) the two lobes of the dorsal division show signs 

 of flattening. In the ventral division, the two posterior lobes have fused to form 

 a single foliate lobe. 



In the 23rd-4oth feet (fig. 4K) the two dorsal lobes gradually grow thin and 

 foliate, and the lower one assumes an anterior position. In the ventral division the 

 upper anterior lobe is gradually reduced to a small papilla, and finally disappears, 

 the ventral division then consisting of two foliate lobes, one on each side of the setae, 

 a conical lobe between them, the ventral ligule and the ventral cirrus. 



Between the 50th and 60th feet a new type of homogomph seta appears (fig. 4N). 

 It is stouter than the others, and the terminal piece is short and smooth, tapering 

 rapidly to a very slender tip. It occurs in the lower part of the dorsal division, and 

 in the upper anterior part of the ventral division. There is no sharp distinction 

 between these setae and the normal homogomphs, intermediate forms occurring both 

 in shape and position. In the 70th foot (text-fig. gk) these thick setae occur also on 

 the lower anterior end of the ventral division. None of the coarsely serrated homo- 

 gomphs were observed after the 35th foot. In the posterior feet the setae become 

 fewer in number, the lobes of the feet greatly reduced, and the whole foot decreases 

 in size. The tips of the shafts of the setae are more swollen than those of the ante- 

 rior segments. 



The anal segment bears two slender anal cirri, equal in length to the last six 

 segments. 



Members of this genus have rarely been found, and only two species have been 

 described. The first of these Dendronereis arborifera, Peters, from the coast of Mozam- 

 bique differs conspicuously in the structure of the branchiae, the main stem of which 

 carries only simple branches. The second species, D. pinnaticirris, Grube (1878, p. 92), 

 from the Philippines, agrees with the present species in the structure of the branchiae. 

 It differs, however, according to Grube, in having no papillae on the proboscis, and 

 in having only 6 teeth on the jaws, as compared with 14-17 in the present species. 

 In D. pinnaticirris, the branchiae begin on the 12th or 13th segments, and there are 

 10-12 pairs of branchiae. InD. aestuarina they begin on the 15th foot, and there are 

 only 8 pairs. In D. pinnaticirris all the branchiae appear to have two rows of com- 



