6o2 Memoirs of the Indian Museum. [Vol. V, 



pound branches, whilst in D. aestuarina the three anterior pairs have only a single row 

 of simple branches. The fully formed branchia of D. aestuarina has more branches 

 than that of D. pinnaticirris . The anterior feet of the present species have many 

 more lobes than those of D. pinnaticirris, but the brief description and figures given 

 by Grube do not permit a close comparison as regards the structure of the feet. A 

 re-examination of D. pinnaticirris would doubtless show other important differences. 



Only a single specimen of D. arborifera has ever been examined, and according 

 to Ehlers (1864-68, p. 581) the proboscis is retracted, and has no paragnaths. It is 

 possible, however, that papillae may have been overlooked on the retracted proboscis, 

 as they are often difficult to observe in this condition. In D. pinnaticirris, according 

 to Grube, there are neither paragnaths nor papillae on the proboscis. Their presence 

 then, in D. aestuarina, was rather a surprise, and I still think it possible that they 

 have been overlooked in the other two species of the genus. 



Habitat.— 19 specimens of this species were collected on the 27th of November, 1911, 

 by Mr. S. G. Platts in the Sunderbans, a district in the Gangetic Delta; and sent by him 

 to the Indian Museum. In a letter accompanying the specimens he gave the follow- 

 ing information : — " The Polychaetous worms I sent you this morning were found by 

 me in a small pool of brackish water inside the protective embankment of a clear- 

 ance fairly high up theMunda river. There were hundreds swimming round and round 

 three or four vortices, and it looked as if they were coming up from the ground at 

 these points. A few minnows were hovering a bout. These used to occasionally pull 

 down a worm, but the fish were either not strong enough to swallow the worms, or 

 the worms were not relished, since they were invariably let go." 



The water in which the worms were despatched was analysed by Mr. David 

 Hooper, who reported as follows : — 



" The sample of brackish water you left with me yesterday contains 833 parts 

 of solid matter and 376-3 parts of chlorine per 100,000 parts. This approximately 

 represents a mixture of three parts of fresh water with one of sea water." 



The two species of Dendronereis previously described were found in sea- water, 

 so that the occurrence of the present species in water almost fresh is of considerable 

 interest. The three known species live on or near the shores of the Pacific and 

 Indian Oceans, and the genus is not known elsewhere. 



Genus Dendronereides, gen. nov. 



The following will serve as a preliminary diagnosis of the genus, until additional 

 species are known: — Proboscis armed only with soft paragnaths. Dorsal setigerous lobe 

 absent in first and second feet. In some of the anterior feet, branchiae are present, in the 

 form of numerous filaments situated below the dorsal cirrus. They are not provided with 

 blood-vessels. Setae of two kinds, falcate homogomphs, and spinose homogomphs. In all 

 feet except a few anterior ones there is a peculiar gland opening to the exterior beneath the 

 dorsal cirrus. The ventral ligule is absent. In the post-branchial region the foot is 

 greatly simplified. 



The presence of parapodia] branchiae in this genus at once suggests relationship 



