282 Transactions of the Society. 



throughout, and so resembling the Lumbriculida3 {Stylodrilus, etc.). 

 The anterior setas appear to be rather longer than the posterior. 

 Large coelomic corpuscles with dark contents. Nerve-chord large 

 and conspicuous. The dorsal vessel forming a kind of heart from 

 segment 5 backwards to the girdle or further, and provided in these 

 segments with strong commissures. As the specimen was im- 

 mature, no penial setje were seen. The presence of the type at once 

 enabled me to see both the resemblances and the differences. I 

 have had no time to look for the worm again, but as the locality is 

 within reach of my residence, I hope shortly to collect more and 

 riper material. 



Locality. — Stream at Netherseal, in Derbyshire. 



IV. Genus Monopylephorus Lev. 



This genus, created by Levinseu in 1884, shows a marked 

 departure from typical Tubiticidas, in the possession of an un- 

 paired male pore. I place here the Vcniuculns of Goodrich 1892, 

 as well as the Bothrioneuron of Stole 1888. Goodrich discovered 

 the type at Weymouth, and details may be found in the usual 

 authorities. 



In 1904 Ditlevsen added two new European species, both of 

 which I have found in the Thames One of the species must be 

 taken from the genus. At present I am working on the material 

 collected in this country, and place two species here. 



1. Monopylephorus ruhroniveus Lev. 



This is one of the few species which I have not as yet been 

 able to study in the living condition. The definitions are given 

 in Beddard (Monograph, p. 268), Michaelsen (Das Tierreich, x. 

 p. 54), and elsewhere. Beddard and Michaelsen give separate 

 accounts of Vermiculus, but I think there is no doubt about the 

 fact that Vermicvlus is one ^vith.3fono2)ylepJwrus {^ = Bothrioneuron). 

 This species is found on the sea coast. I have no doubt it will be 

 discovered in due course in the Thames estuary, where I have had 

 the good fortune during the past year to obtain so large a number 

 of interesting species of Tubificids, including the next, which is 

 new to Britain. 



2. Monopylephorus parvus Ditlevsen. 



Two to five forked setas in the front dorsal bundles. The teeth 

 are small and of equal lengths, or the upper is a little longer than 

 the under tooth. The setpe in the dorsal bundles posteriorly are 

 not forked. In the ventral bundles there are three to five forked 

 setae, in which the upper tooth is a little longer than the lower. 



