380 MR. F. E. BEDDARD OS TWO [Apr. 17, 



Western than in Eastern Africa. I bave already described several 

 species of a genus nearly confined to Western Africa, viz. Gordio- 

 drilus ; and at Lagos a species of Pygmceodrilus also exists. The 

 same two genera also occur on the West Coast, but the former is 

 there not nearly so common. The present paper increases the 

 number of West-African Cryptodrilida by three; and I refer these 

 worms to two new genera. Nannodrilus africanus seems, from the 

 large number of specimens sent to me, to be an exceedingly 

 common species. 



It is a curious fact that both of the two genera show certain 

 resemblances to the Eudrilida? : there is, in my opinion, little doubt 

 but that the Eudrilidae are derivatives of the Cryptodrilidae ; but I 

 cannot agree with those who would unite two such extremely 

 diverse types in one famdy. I shall now direct attention to the 

 anatomical characters of the new species, beginning with a defi- 

 nition of the first genus, which I propose to call after Mr. Alvan 

 MiJlson. 



Jlillsonia, gen. nov. 



Def. Large worms with strictly paired setce. Male pores (single 

 or paired) upon xvii. Two gizzards in v., vi. ; calciferous 

 glands, three pairs in xv.—xvii. ; intestine with about 30 pairs 

 of caeca, a pair to each segment. Nephridia diffuse. One 

 pair of spier mathecce without diverticula ; spermiducal glands 

 tubular ; no penial setce. — Hab. West Africa. 



This definition will differentiate the present genus from any 

 other Cryptodrilid at present known. The two most salient 

 characters of the genus which are peculiar to itself concern the 

 nephridia and the intestinal caeca. These alone would serve to 

 distinguish the genus ; it is principally on account of them that I 

 unite the two species, which I shall describe, into a single genus. 

 These two species, as will be seen in the course of the following 

 pages, differ from each other in a good many points of, as I 

 believe, subsidiary importance. The two matters referred to are 

 not exactly novelties of structure in the group, but they are 

 exaggerations, so to speak, of characters already found in allied 

 forms. The caeca are precisely like those of the genus Perichceta 

 only that there are so many of them. In Perichceta sieboldi and in 

 one or two other species there are, it is true, six or seven pairs of 

 these appendages of the intestine ; but then they are all contained 

 in one segment ; whereas in the genus Millsonia they are contained 

 in as many segments as there are pairs of caeca. The existence of 

 these caeca is interesting as tending to knit still closer together the, 

 in other ways not very remote, Cryptodrilidae and Perichaetidae. 



The second peculiarity of this genus concerns the nephridia. 

 The structure of these organs will be described more at length 

 immediately ; but in the meantime attention may be directed to 

 the fact that they present the curious appearance illustrated in the 

 accompanying drawing (fig. 1, p. 381). The excretory tubes of 

 the posterior segments of the body have ceased altogether to look 



