62 



Memoirs of the Indian Museum. 



[Voi,. V, 



chus, the only differences detected being that the processes of the nephridial funnels 

 were less distinctly coiled and the anal trees possibly longer. In the fully expanded 

 specimen the latter are about half as long as the body, but it was noticed in the 

 living animal that their relative length varied with the state of general expansion and 

 that they were not so extensile as the body as a whole. The arrangement and form of 

 the minute funnels on the trees seem to be identical in the two species. 



Our specimen from the Gangetic delta was active. When placed in a dish of mud 

 and water, the animal formed for itself, by irregular movements of the body and probos- 

 cis, a shallow groove on the surface of the mud. It made no attempt to burrow down- 

 wards, but lay on one side in this groove. When first removed from the water it 

 writhed vigorously and changed its shape rapidly in diverse regions, sometimes 

 extending itself to a considerable length and assuming a worm -like form, sometimes 



c- 



Fig. 3. — Thalassema branchiorhynchus , sp. nov. 



Gill-like outgrowth from base of proboscis, seen from ventral surface, x 30. 



c = lumen of base of outgrowth, which is cut off a little obliquely ; m = muscles entering base. 



expanding the extremities or other parts of the body into bulbous or annular swell- 

 ings. When it was replaced in its natural element these movements continued for a 

 short time, but soon became less vigorous, though without ceasing completely. The 

 natural attitude of the proboscis appeared to be rlexed backwards, so that its dorsal 

 surface was in contact with that of the body. The distal parts of the lateral borders 

 were applied together so as to form a complete tube ; but the proximal parts were 

 everted (fig. 2, p. 58), the dendritic outgrowths being thus displayed. They were some- 

 what contractile and, when fully extended and spread out, formed a double series of 

 short feathery tentacles. The whole proboscis was, however, sometimes twisted spir- 

 ally, as is shown in the figure. 



The only known specimen of T. branchiorhynchus was taken in about 3 feet of 

 water in a small tidal creek connected with a canal near Chingrighatta on the out- 

 skirts of Calcutta in December, 1914. The specific gravity of the water was then 

 l'ooô. 



