598 Memoirs of the Indian Museum. [Vol,. V, 



Dendronereis aestuarina, sp. nov. 

 (Plate XX, figs. 4A-N, and text-figs, ga-h.) 



Nineteen specimens of this species were obtained in brackish water in the 

 Gangetic delta, in very good condition. 



The type specimen is 160 mm. long, and consists of 160 setigerous segments. It 

 is a female, full of immature ova. In life the body is reddish brown, the colour being 

 probably due to the blood, and the gills and dorsal vessel are bright red. The body 

 in front of the gills is much darker, and appears to be coloured with brown pigment.' 

 The preserved specimens are colourless. On the ventral surface of segments 3 — 13, 

 in the median line, there is in all specimens a definite pattern of grooves (fig. 4c). 



The head (fig. 4A) is deeply indented in front, where it bears two small tentacles. 

 The posterior part is short and wide, with rounded corners. It bears two pairs of 

 large eyes, the pair on each side being close together. In front the head is prolonged 

 into the two large conical palps. The peristomium bears four pairs of tentacular 

 cirri, with large jointed ceratophores. The posterior dorsal pair are much the longest, 

 and when laid backwards they reach to the end of the 9th setigerous segment. They 

 are nearly three times as long as the posterior ventral pair, and 2\ times as long as 

 the anterior dorsal pair, whilst the latter are nearly twice as long as the anterior ven- 

 tral pair. 



The proboscis (figs. 4A, 4B) is not armed with horny paragnaths, but on the 

 anterior border of the basal segment it carries a number of papillae. Of these the 

 two largest are near the median dorsal line. On the ventro-lateral region there are 

 two on each side, and there are three smaller ones in the median ventral area. The 

 papillae are pear-shaped or fusiform. The whole of the basal segment is covered 

 with low rounded papillae, but these are probably produced by the contraction of 

 the proboscis in the preservative, and have no relation to the papillae on the anterior 

 margin. The maxillary segment is devoid of papillae. The jaws have 14-17 teeth, 

 2 or 3 at each end of the row being indistinct. 



The branchiae commence on the 15th foot (fig. 4F). Each branchia consists 

 essentially of the greatly enlarged, flattened, and branched base of the dorsal cirrus. 

 The dorsal cirrus itself is, as usual, a simple lobe, attached to the tip of the enlarged 

 base. Two large blood-vessels traverse the main stem, giving off or receiving 

 numerous branches which divide several times, and penetrate the filaments. Apart 

 from the vessels in the filaments, there are numerous capillaries in the walls of the 

 main stem of the branchia. In the ist branchia (fig. 4F) there are 8 clavate lobes 

 on the outer edge of the main stem. They are slightly contracted at the base, and 

 diminish in size towards the tip of the stem. The 2nd pair of branchiae resemble the 

 ist pair. The 3rd pair, on the 17th feet (fig. 4G), have each 10 filaments, and indica- 

 tions of another row on the outer side of the stem. The 4th pair, on the 18th feet, 

 show the complete development of the branchiae (fig. 4H). The main stem is almost 



• ] This description is from a coloured figure, drawn from a living specimen, by A. Chowdhary. 



