138 Proceedings of the Royal Irish Academy. 



The commissures are also large and broad. The pharynx reaches back 

 to the 5th segment. The intestine is covered with very dark-brown 

 cells. There are prominent contractile vessels in segments 8 and 9. The 

 nephridia are almost completely enveloped in a mass of clear spherical cells. 

 The spermathecEe consist of a pear-shaped sack, which leads through a 

 narrow opening into a broad thick-walled duct, opening by a narrow slit on 

 the 10th segment (fig. 5, c). No spermatophores were observed. The 

 sperm duct (fig. 5, d) commences with a cone-shaped funnel, which leads into 

 a long narrow duct ciliated during the latter part of its course. This passes 

 into a broad atrium lined with very characteristic irregular branched masses 

 of cells. At about the middle of its length it receives the large prostate 

 gland. The penis-sheath is 9-12 times as long as broad. It is curved in a 

 very irregular manner, and becomes very narrow distally, before expanding 

 into a funnel-like mouth (fig. 5, e) . The distal end is of somewhat complex 

 structure. It is sometimes bent at right angles (fig. 5, E, d), but usually 

 only slightly curved. The length in all cases was very close to 300//, the 

 width 25-35//. The width of the proximal end varies; and this accounts 

 for the variation in the relative proportions. The length is slightly less 

 than the width of the body. 



Mature — February to April. 



Habitat — Ireland. Pond near Montpelier, Co, Dublin; E. Annalee, 

 Ballyhaise, Co. Cavan. 



England. E. Douglas, Adlington, Lancashire. 



Tubifex tubifex (Miill.). 



1851. Nai8 filiformis, Williams in Eep. British Assoc, vol. xxi., p. 264, 

 Plate 8, fig. 72. 



The species referred to by Williams {torn, cit.) as Nais filiformis, 

 Ant. Dug., would appear to be TuMfex tiibifex (T. rimdorum auct.). 

 Michaelsen (21, p. 51) refers it doubtfully to T.fcrox (Eisen) ; but the shape 

 of the spermatophore and its arrow-like head point to T. tuhifex. 



Mature — March, April, May, October. 



Habitat — Ireland. Co. Dublin (Carrickmines, &c.) ; Co Wicklow (Pond 

 near Scalp). 



England. E. Douglas, Adlington, Lancashire. 



Distribution — British Isles ; Europe ; North America. 



