22 Mr. H. J. Carter on the ^perinatology of a new species of Nais. 



ventral, in pairs in each segment throughout the body ; each 

 cirrus composed of 2-4 short, sigmoid, stiff hairs, suddenly- 

 inflated in the centre and bifid at the extremity. Setae (fig. 4) 

 in groups in pairs in each segment after the posterior border 

 of the reproductive band, each group composed of 2-3 straight 

 hairs, of which one is much larger than the rest, and equal in 

 length to the breadth of the body. (Esophagus narrow, 

 without distinct glands, expanding gradually into the intes- 

 tine at the posterior limit of the reproductive band. Intes- 

 tine wavy at first, afterwards straight, subsegmented, of a 

 brown colour tinged pink by the vascular system, which con- 

 tains red blood. Androgynous. Testicular sacs immediately 

 in front of the reproductive band ; oviducts and ovisacs under 

 and posterior to it respectively; openings of the testicular 

 sacs close to the anterior border of the reproductive band on 

 each side. Spermatozoon (fig. 6 b) linear, straight, extremely 

 narrow, with attenuated extremities, l-160th of an inch in 

 length. Segmental organ single, existing only in those divi- 

 sions which are behind the reproductive band. Floating-cells 

 of the peritoneal cavity spherical, colourless. Length of body 

 when dry a little less than l-5th of an inch. 



Hab. Tanks and ponds of fresh water among soft, silky Oscil- 

 latoria and decomposing vegetable matter ; breeding through- 

 out the year. 



Loc. Island of Bombay. 



Obs. This worm, which belongs to the genus Blanonais 

 (P. Gervais), is very like the figure of Lumbricus tubifex (pi. 34. 

 fig. 4 a, Encyclop. Meth.), while the setae of the latter more 

 resemble those of the following species. 



Nais albida, H. J. C. (nov. sp.) PI. III. figs. 47, 48. 



Filiform, colourless or white, obsoletely segmented; anterior 

 extremity obtusely pointed, posterior extremity obtuse ; mouth 

 subterminal ; anus terminal. Reproductive band a long di- 

 stance from the head, commencing about the tenth segment. 

 Cirrus and setae (PL III. fig. 49) retractile, both composed of 

 minute, short, straight, thick hairs, all alike and of equal length, 

 three in the former and two in the latter, situated ventrally 

 and laterally respectively, in pairs in each segment throughout 

 the body. (Esophagus narrow, surrounded in its first part 

 by four distinct glandular masses, then by hepatic cells, then 

 becoming naked as it passes under the reproductive band, at 

 the posterior border of which it expands into the intestine. 

 Intestine at first wavy, and then straight to the anus. Andro- 

 gynous. Testicular sacs indistinct, situated just in front 



