Southern — Monograph of the British and Irish Oligochwta. 137 



a slender branching nerve. The commissures are very wide, and project 

 far in front of the brain. There are contractile vessels in the 8th and 9th 

 segments. In the posterior segments there is only a single integumental 

 commissure between the dorsal and ventral vessels. It lies at the back of 

 the segment, and does not branch, thus differing markedly from L. Hoffmeisteri 

 Clap. The first nephridia are in the 6th segment. The anterior nephridia 

 (fig. 3, d) are enveloped in a compact mass of bladder-like cells. The duct is 

 widened at the pore. The post-clitellar nephridia are not enveloped in these 

 cells. 



The spermatheca (fig. 3, e) consists of a large sac which leads by a narrow 

 passage into a wide duct. The duct is proportionately much smaller than in 

 L. parvus. The spermathecee each contain 2 or 3 spermatophores. These 

 (fig. 3, f) are compact, oval bodies, with rounded ends. At the broad end is 

 a clear oval space containing several shining granules. The atrium is very 

 long and slender, and is swollen in the middle, where it receives the prostate 

 gland. The penis is 8-9 times as long as the proximal end is broad (fig. 3, g). 

 It is curved distally, and terminates in a funnel-like enlargement, which is 

 twisted on one side into a sharp-pointed beak. 



This species seems to be most nearly related to L. Hoffmeisteri Clap. 

 The chief differences are : — 



(1) The pharynx reaches back to the 5th segment; 



(2) Integumental vessels not branched ; 



(3) Shape of the setse and penis-sheath ; 



(4) Shape of the spermatheca and spermatophores. 



Mature — April . 



Hahitat — Pond at Carrickmines, Co. Dublin, 



Limnodrilus parvus n. sp. 



Plate viil, fig. 5, a-e. 



This species is of comparatively small and slender dimensions, being only 

 12-15 mm. long. The prostomium is rounded; and the breadth at the base 

 exceeds the length. The epidermis is smooth, and the segments not bian- 

 nulate. There are 3-5, usually 5, setse in the anterior dorsal and ventral 

 bundles. The lower tooth of the seta is slightly longer and thicker than 

 the upper one (PI. vii., fig. 5, a). The node occurs at the beginning of the 

 distal third. The brain (fig. 5, b) has a rounded outline, and is deeply concave 

 behind. The front is slightly convex, and has a broad median outgrowth. 



