| OCR Text |
Show 494 MR. BEDDARD ON THE STRUCTURE OF CLITELLIO. [Dec. 4, C. arenarius. C. ater. 1. Setce Bifid sete only pre- Bifid and hair-like setae in sent. the dorsal bundle; only bifid setae in the ventral bundle. Sometimes no hair-setas. 2. 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 11th segment. Extre-through several seg- mity of vas deferens dilated ments. into a special chamber. 4. Prostate Absent. Present. 5. Spermatheca Specialized into two Not specialized; confined to regions ; extending one segment. through several segments. 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 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 chitinous, 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 H. 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 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 this paper. On the whole it seems advisable to retain the generic name Clitellio for C. arenarius, and it m ay be thus characterized :- CLITELLIO, Claparede. Clitellio, Claparede, " Etudes anatomiques, & c , " M e m . 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 11th segment. Egg-sacs in segments 13, 14, 15. Spermathecae very large, occupying several segments, differentiated into two regions, separated by a constriction. Spermatophores elongate. This genus will only contain C. arenarius 2. Clitellio ater must, I think, be included in Eisen's genus Hemitubifex. 1 Tt should be mentioned that the effect of the two rivers which enter the Sound at Plymouth, and the breakwater which extends across its mouth, is to render the water somewhat brackish. a The other species of the genus must be regarded with Vejdovsky as " inccrtm sedis." |
