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



C. arenarius. C. ater. 



1. Set(B Bifid setae ouly pre- Bifid and hair-like sette in 



sent. the dorsal bundle ; only 



bifid seta; in the ventral 



. bundle. Sometimes no 



hair-setse. 



'^. 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- niitj of vas deferens dilated 



ments. into a special chamber. 



4. Prohtate Absent. Present. 



6. 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 

 spermatheese only differ in being without the glandular appendices 

 which Eisen figures in Hemitubifex insignis. 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-setae 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 chilinous, because this character does not differentiate the 

 two species which are compared in that Table ; it does, however, 

 distinguish Hemitubifex from Tubifex. 



Eisen met with //. insignis 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 that genus in much 

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

 Mas 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 te.\t of tliis paper. On the 

 whole it seems 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. Phys. 

 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- 

 matheese 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 whidi enter tlie 

 Sound at Plymouth, and (he breakwater which extends across its mouth, is to 

 lender the water somewliat brackish. 



^ The other species of the genus must be regarded with Vejdovsky as " inccrtce 

 scdis." 



