DESCRIPTIONS OF GENERA AND SPECIES 255 



(lo) Limnodrilus igneus, Eisen. 



Camptodrilus igneus, Eisen, loc. cit., p. 23. 



Clitellio (Limnodrilus) igneus, Vaillant, loc. cit., p. 430. 



Definition. Length about 30 mm. Brain deeply cleft in front and behind ; the two 

 anterior lateral processes of the brain marked by several protuberances, broader in front 

 than behind. Nephridia with, vesicular peritoneal cells. Spermathecae wide distally ; 

 expanded at its extremity. Penis at least ten times as long as broad. Hob. — San 

 Francisco. 



Genus Hesperodrilus, Beddaed. 



Defikttiobt. Dorsal seta bundles with capilliform setae only; ventral setae 

 uncinate and simple, one of each, kind in a bundle. Clitellum XII -XIII ; 

 male pores on XIII, spermathecae open on XIII. Ko prostate. 



This genus is at present known only from South America, whence I have described 

 four species. The genus, though agreeing in general appearance with Tubifex and 

 other Tubificidae (the resemblance is not so marked in the case of Hesperodrilus 

 niger), is one of the most distinct of the genera of this family. As regards external 

 characters the position of the clitellum and of the generative pores differs from all 

 other Tubificidae — if we assign to that family, and except only, Phreodrilus. The 

 segments occupied by these various structures are one further back than is usual. 

 The setae of the ventral bundles are remarkable for the fact that in each bundle 

 there is one uncinate seta and one whose extremity is not bifid. In two species, viz. 

 H. albus and H. pellucidus, the dorsal setae are wanting upon the first setigerous 

 segment, thus recalling the state of affairs so characteristic of the Naidomorpha. The 

 iaternal structure is chiefly remarkable for the fact that the sperm-duct does not 

 open into the summit of the spermiducal gland, but opens in common with this 

 gland into the base of the protrusible penis. There are no distinct prostates ; nor 

 is the absence of these compensated for by the presence of a thick glandular covering 

 such as occurs in Branchiura. The spermathecae are abnormal in opening on to the 

 exterior behind the male pores — a quite unique occurrence in the family excepting 

 again only Phreodrilus. Coupled with the absence of prostates, there are no spermato- 

 phores. Of the four species of this genus two come very close together, viz. H. albus 

 and H. pellucidus. The species can be discriminated by the following scheme : — 

 (i) Setae absent from dorsal region of first two segments : 



a. Spermiducal gland with narrow duct leading to penis. H. albus. 



