186 OLIGOCHAETA 



A. niveum in which there are two kinds of setae. The capilliform setae resemble those 

 of other species, but the sigmoid setae are peculiar to this species and to A. leidyi and 

 A. niveum ; they are like those of Naids, bifid at the free extremity ; these setae are 

 found in the dorsal and ventral bundles, from the fourth setigerous segment onwards. 



It should be remarked that in the specimens described by myself under the name of 

 A. tenebrarum the sigmoid setae of the posterior segments ave not bifid. I examined 

 them with great care and with high powers, but could not detect the least notch at the 

 extremity of the setae. The colour of the oil globules, too, does not agree with 

 Vejdovsky's description or coloured figures of A. tenebrarum. These worms may 

 therefore possibly belong to a distinct species. 



(6) Aeolosoma headleyi, Beddakd. 



A. headleyi, Beddakd, P. Z. S. 1888, p. 313. 



Definition. Of moderate size ; setae entirely capilliform. Integumental globules bright-green, 

 occasionall)/ verging towards blue. First nephridium in first setigerous segment ; nine or ten 

 pairs altogether. Habitat? [found in a tank at Zoological Gardens, London). 



This species evidently comes nearest to A. variegatum, but is to be distinguished 

 by large number of nephridia. 



(7) Aeolosoma niveum, Leydig. 



A. niveum, Leydig, Arch. f. Anat. u. Phys. 1865, p. 360. 

 A. laeteum, TiMM, Arb. Zool. Zoot. WUrzb. 1883, p. 155. 

 ? Chaetodemus panduratus, Leidy, P. Aca(J Nat. Sci. Philadelphia, V. 185a, p. 286. 



Definition. Prostomium not wider than folloiving segments. Setae sigmoid and capilliform. 



Integumental globules colourless ; only one pair of nephridia, at end of oesophageal region. 



This species was described and figured by Leydig (4). It is of very minute size, 

 apparently smaller even than A. quaternarium and A. variegatum. Leydig thought 

 that it was possibly the young of ' ^. decorum ' of Eheenbeeg, but pointed out that 

 this was rendered less likely by the fact that Ehrenbeeg observed the red-coloured 

 oU-drops of the latter species while yet within the egg. In all probability the ' ecrgs ' 

 mentioned by Eheenbeeg are the cysts which I have described, and thus this 

 argument falls to the ground. Vejdovsky thought that his A. variegatum might be 

 the same. The same form was found in the Main by Timm, and mentioned under 

 the name of 'Aeolosoma laeteum, Leydig' — doubtless a slip of the pen. I have 

 contributed a few notes (25) upon this species, pointing out the existence of sigmoid 



