150 Proceedings of the Royal Irish Academy. 



setae in a bundle. In this respect it resembles L. verrucosus (Clap.) more 

 closely than L. lineatus, which has 5 setse in a bundle. This identification 

 is more probable also, because L. verritcosus is one of our commonest littoral 

 forms. 



Lumbricillus subterraneus (Vejd.). 



1889. Pachydrihis s., Vejdovsky in Rev. Biol. Nord France, vol. i., p. 121. 



In May, 1907, Professor G-regg Wilson sent me a large number of worms 

 from the sewage works at Belfast, where they occurred in such numbers as to 

 be a serious nuisance. These worms agreed in structure with those described 

 as L. subterraneus by Vejdovsky (tom. cit.), who obtained them from the under- 

 ground waters of Lille and Prague. The Belfast worms are also probably of 

 subterranean origin. In April, 1908, I found the same species in large 

 numbers in a stream at Adlington, Lancashire. This stream is excessively 

 contaminated with trade effluents. A preparation of iron and aluminium is 

 used to purify the stream ; and this forms a thick gelatinous layer on the bed 

 of the river. This layer is crowded with vast numbers of this worm, 

 accompanied by Tuhifex tuhifex, Limnodrilus udekemianus, and a species of the 

 Nematode genus Mermis. 



The worms are 12-18 mm. long. The anterior ventral bundles contain 

 5-7 setae. The cuticle is smooth and without glands. The sperm athecae are 

 spindle-shaped, and without sharply defined duct, and are surrounded at the 

 base with prominent glands. The dorsal vessel rises in the 14th or 15th 

 segment. The copulatory glands vary greatly. Sometimes large glands 

 occur in the 13th and 14th segments ; sometimes they are small, or quite 

 absent. The brain, nephridia, and genital organs agree with the description 

 of Vejdovsky, 



April, May. 



Habitat — Ireland. Belfast. 



England. Adlington, Lancashire. 



Distribution — Prague ; Lille. 



Lumbricillus litoreus (Hesse). 



1893. Pacliydrilus litoreus, Hesse in Z. wiss. Zool., vol. Ivii., p. 3. 



The only differences between this species and L. Ii7icatus (Mtill.) appear to 

 be (i.) number of setse in a bundle ; (ii.) the structure of the copulatory 

 glands ; (iii.) the nature of the glands at the spermathecal pore. None of 

 these differences seem of great importance ; and it is doubtful whether there 

 is sufficient justification for keeping the two species separate. I have found 

 specimens in soil and in brackish water which agree with L, litoreits on these 



