264 W. B. BENHAM. 



species of Lumbricus and Allolobophora ; and unknown 

 elsewhere. 



Criodrilus, in fact^ must be regarded as a degenerate 

 Allolobophora^ owing to its altered mode of life; its 

 aquatic habit has no doubt a connection with the absence 

 of a gizzard, and very likely with the absence of nephridia in 

 the anterior somites, which may probably be used in ordinary 

 earthworms as salivary glands — that is, for the purpose of 

 moistening the food. At any rate, we find the same absence 

 of anterior nephridia in another aquatic form, Pontodrilus; 

 and the fact that in so many worms the anterior nephridia are 

 specially large, or modified in some way (as in Urochaeta, 

 Diachseta, &c.), and even open into the pharynx instead of 

 externally, bears me out in this idea. 



In this connection it is interesting, though contradictory, 

 to find that AUurus, which is also an aquatic form, but lives 

 in the soil below the water, whilst Criodrilus lives actually 

 in the water, has nephrida in the anterior somites. 



Allurus has no true spermathecse. Beddard describes a 

 minute sac embedded in the body wall, and opening exter- 

 nally on the somite, but no spermatozon were observed in it ; 

 and it may perhaps be either degenerate, or of the nature of 

 an albumen {" capsulogenous '^) gland. 



The species both of Lumbricus and Allolobophora are 

 in a state of great confusion ; even modern authors make two 

 species out of one, or split up one into two. The list I have 

 given is taken from Vejdovsky's ' System und Morphologic,' 

 with additional species described since the date of his mono- 

 graph. 



Incertse sedis. 

 Helodrilus, Hoffmeister, 1845. 



Setse black, in couples. 



Clitellum absent. 



Spermiducal pores on Somite xv. 



Gizzard present. 



Pigment spots are present on peristomial somite, but are 

 absent in young individuals. 



