256 OLIGOCHAETA 



b. Spermiducal gland without this duct. H. pellucidus. 

 (2) Setae present upon all segments after the first: 



a. Posterior end of body with branchiae. H. branchiatus. 



b. No branchiae. H. niger. 



(i) Hesperodrilus albus, BEDDAKD. 

 H. albus, BEDDARD, Ann. Mag. Nat. Hist. Feb. 1894, p. 209. 

 Definition. Setae of dorsal bundles commence in segment III. Spermiducal gland opens 



info penis by a moderately long, narrow, non-glandular duel. flab. Port Stanley, 



Falkland Islands, in a pond. 



This species, in the preserved condition, was quite white ; hence the specific name. 

 It is about the size of a Tubifex. The intestine begins in xix. The first pair of 

 nephridia, which occupy segments vi-x, open on to the exterior in vi. The condition 

 of this first pair and they are the same in the following species recalls a character- 

 istic feature of the Lumbrindid Pkreatothrix. The sperrnathecae are very peculiar 

 apart from the position of their external pore. They are very long, extending through 

 five segments. The blind extremity is dilated into an oval sac ; in which part of the 

 organ alone was sperm to be found. Then follows a narrow duct which runs in 

 a fairly straight course, being in one specimen wound round the corresponding part 

 of the spermatheca of the opposite side of the body. In the middle of this is a kind 

 of trap formed by a sudden increase in the height of the lining epithelium, and diameter 

 of the tube, which projects forward, and would tend to prevent the sperm from moving 

 except in one direction, i. e. towards the blind end of the sac. After the narrow part 

 of the tube it widens out into a terminal chamber, which opens on to the exterior 

 in the unusual position already referred to. The Spermiducal gland is not large ; it 

 ends in a thin tube lined by a non-glandular lining which opens into the penis. In 

 one individual the clitellum occupied segments xi, xii, the normal segments for the 

 Tubificidae. The entire spermiducal gland can be everted, and the penis thus formed 

 is very long. There were ripe ova in segments xviii-xx, or in xxi, xxii. 



(2) Hesperodrilus pellucidus, BEDDARD. 

 H. pellucidus, BEDDARD, loc. cit., p. 210. 



Definition. Setae of dorsal bundle commence in III. Setae of dorsal bundles shorter and 

 more slender t/ian in last species. No long duct, only a constriction separates spermidncal 

 gland from penis. Hab. VscJmia, S. America. 



This species exactly resembles the last, except in the points noted in the above 

 diagnosis and in the pale brown colour of the preserved worms. 



