204 Records of the Indian Museum. [Vol. VI, 



Aeolosoma bengalense , sp. nov. 



Found in the Museum tank, Calcutta, Nov. loth 1910, C. 

 Paiva. Mr. Gravely 's accompanying note stated that the oil- 

 globules were of the colour of blue-green algae, the stomach deep 

 orange. 



In the preserved condition the specimens were white in 

 colour, I — 1| mm. long, and '2 — '3 mm. broad. The prostomium 

 was semicircular in shape, and no broader than the succeeding 

 segments; conspicuous cilia clothe its ventral surface. 



The largest number of segments noted in an animal which 

 did not show any signs of approaching fission was fourteen. 

 Other specimens of fourteen segments showed the beginning of 

 an approaching division after the eleventh, or perhaps after 

 the tenth segment ; specimens with larger numbers of segments 

 also showed a line of division after the eleventh segment. I 

 cannot state what number of segments, if any, are intercalated at 

 this point before division takes place, since in none of the speci- 

 mens examined were there any newly forming groups of setae 

 in this region. 



The setae are all of the capillary type ; dorsal and ventral 

 series both begin in the same segment (ii). The setae are quite 

 straight, long and thin, tapering gradually to a very fine point. 

 In each bundle there is as a rule one, or sometimes two, long setae 

 together with a few shorter ones ; this difference in length is 

 a real difference of type, since no setae of intermediate lengths 

 occur; all the shorter setae are of approximately the same length, 

 while the long seta of the bundle is very considerably longer, 

 and it may be added considerably thicker also. This may be 

 illustrated by the following figures, which give the lengths of 

 the setae in fx in nine bundles ; the figures in heavy t3^pe represent 

 the lengths of the long, the other figures those of the short setae, 

 (i) 234, 122, 112, 112, 108. (2) 187, 122, 122, 112. (3) 234, 112, 

 103. (4) 244, 141, 108. (5) 206, 122, 122, 112, 94. (6) 178, 112, 

 112. (7) 169, 141, 103, 94. (8) 234, 103, 103. (9) 225, 103. 



The average length of the long setae is thus nearly twice that 

 of the short ones ; and since the above measurements are taken 

 from the bottom of the setal sac, the disparity in length between 

 those portions which project beyond the body-wall is still greater. 



Bundles of setae were sometimes seen without any long setae ; 

 usually there was one, occasionally two; it is possible that in those 

 cases where none was seen, one may have dropped out. The 

 shorter setae were usually two, three or four per bundle. 



The buccal cavit3^ is large, in the shape of a narrow bell, 

 placed vertically in segment i ; it is lined by a tall epithelium. 

 The oesophagus, beginning at the dorsal end of the buccal cavity, 

 occupies segments ii and iii, and is somewhat sinuous. The 

 stomach extends from iv to viii, and is the widest part of the 

 alimentary tube; the intestine begins in ix and extends to the 

 posterior end. 



