494 MR. BEDDARD ON THE STRUCTURE OF CLITELLIO. [DeC. 4, 



C. arenarius. C. ater. 



1. 6'ete Bifid sete only pre- Bifid and hair-like sette in 



sent. the dorsal bundle ; only 



bifid seta in the ventral 

 bundle. Sometimes no 

 hair-setae. 



'Z. Vas deferens Short and wide. Long and slender and much 



coiled. 



3. Atrium Long and bent upon Shortand straight, confined to 



itself, or extending the lltli segment. Extre- 



through several seg- mity of vas deferens dilated 



meuts. into a special chamber. 



4. Proitate Absent. Present. 



5. Spermatheca Specialized into two Not specialized ; confined to 



regions ; extending one segment, 



through several seg- 

 ments. 



Clitellio ater agrees in Nos. 1, 2, 3, 4 with Hemitubifex, and the 

 spermathecae only differ in being without the glandular appendices 

 which Eisen figures in Hemitubifex insignia. This latter point is 

 one which I should regard as being only of specific value. It is 

 only by the occasional absence of the hair-setse in the dorsal rows, 

 and the dilatation of the vas deferens, that this species differs from 

 Tubifex. I have not mentioned in the Table the fact that the 

 penis is chitinous, because this character does not differentiate the 

 two species which are compared in that Tal)le ; it does, however, 

 distinguish Hemitubifex from Tubifex. 



Eisen met with H. insignia in Sweden, in fresh water, so that its 

 habitat is rather different from that of Clitellio ater *. 



Clitellio arenarius agrees with Ilyodrilus in having a short thick 

 efferent duct, but it does not appear to resemble tbat genus in much 

 else except perhaps in the absence (?) of prostate glands. Stole 

 was unable to find these glands in Ilyodrilus coccineus; Eisen, 

 however, figures them in several species, though apparently their 

 presence is not referred to in the text of tliis paper. On tlie 

 whole it ?eems advisable to retain the generic name Clitellio for 

 C. arenarius, and it may be thus characterized : — 



Clitellio, Claparede. 



Clitellio, Claparede, " Etudes anatomiques, &c.," Mem. Soc. Phvs. 

 Geneve, t. xvi. 1862, p. 102. 



Marine Tubificidae of an elongate slender form. Bifid setae only. 

 Vas deferens wide and short ; atrium very long ; no vesicula seminalis ; 

 no prostate glands ; penis with a chitinous covering. Oviduct 

 present in 1 1th segment. Egg-sacs in segments 13, 14, 15. Sper- 

 mathecae very large, occupying several segments, differentiated into 

 two regions, separated by a constriction. Spermatopliores elongate. 



This genus will only contain C. arenarius '. 



Clitellio ater must, I think, be included in Eisen's genus Hemitu- 

 bifex. 



' It should be mentioned that the effect of the two rivers which enter the 

 Sound at Plymouth, and the breakwater which exteiida across its mouth, is to 

 render the water somewhat brackish. 



* The other species of the genus must be regarded with Vejdovsky as " iiiccrt<s 

 sedis." 



