154 Proceedings of the Royal Irish Academy. 



The worms are 10-15 mm. long. The anterior ventral bundles contain 

 5-7 setse, the lateral ones 4-6. The setae are not so curved, nor are they 

 arranged in such a fan-shaped manner, as is usual in this genus. The 

 epidermis of each segment is composed of several rings (PI. XL, fig. 12, e) 

 formed by lines of fine dotted glands ; and each ring has several rows of clear, 

 oval glands. Contrary to the usual rule, these rings are even more prominent 

 in the posterior than in the anterior segments. The clitellum occupies 

 segment 12. It is formed of rows of very small granular glands. The 

 prostomium and 1st segment are covered with small papillse, probably 

 sensory in function. The head-pore is situated between the prostomium and 

 the 1st segment. It is small and round. 



The brain (Plate XI, fig. 12, f) is somewiiat longer than broad. It is 

 deeply emarginate behind, and straight or slightly concave in front, and the 

 sides are almost parallel. The ccelomic corpuscles (PL x., fig. 12, b) are very 

 thin and fragile in appearance. 'J'heir contents are faintly granular, with 

 a clear spot in the middle. They are so thin as to be bent into folds 

 as they flow about in the ccelomic fluid. They are of various shapes, and 

 resemble those of Marionina arenaria, which Michaelsen has figured 

 (20. fig. 5, a). In some of them the ends are drawn out into fine points. In 

 others one side is rounded, and the other drawn out into a number of fine 

 pseudopod-like processes, which may be branched. There are three pairs of 

 septal glands in the 4th-6th segments. The nephridia (PI. x., fig. 12, c) are 

 composed of a long, slender anteseptal, and a large, flat postseptal, which 

 passes gradually into a long duet. 



The dorsal vessel rises between the 13th and 14th segments. The copulatory 

 glands are A^ery small, and seem to occur only in the 14th segment. The 

 spermathecffi (PI. x., fig. 12, d) are in the normal position, and communicate 

 with the oesophagus by a narrow duct. The ampulla is oval in shape, and is 

 shorter than the narrow duct. The latter is surrounded at the pore by a 

 massive collar of glands. The testes are lobed, and occupy the 10th segment. 

 The sperm-funnels are very variable in shape ; and the relative proportion of 

 length to breadth varies from 4-7 according to the tension on the organ. 

 The lip is prominent and usually slightly folded. The duct is long and coiled, 

 and ends in a large prostate. 



This species is chiefly characterized by its dark colour and the structure 

 of its nephridia, spermathecse, and ccelomic corpuscles. 



January. 



Habitat — Ireland. Under stones in the littoral zone, at Balkey, Co. 

 Dublin. 



