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Show 228 MB. F. E. BEDDARD ON NEW EABTHWOEMS. [Mar. 19, Eisen allows three genera of worms where I only allow the genus Microscolex. These genera are of course m y Rhodoclrilus and Eisen's Deltania in addition to Microscolex. Deltania is distinguished from both by the closer approximation of each pair of ventral setae in the segments near to the xviith. Rhododrilus is distinguished from both by the separate opening of sperm-ducts and spermiducal glands. This latter character will hardly suffice as a mark of distinction ; there are so m a n y intermediate conditions in the genus Microscolex (s. s.). In M. gracilis the two unite well within the body-cavity ; in M. novce-zealandice just at the common orifice ; in M. papillosus the external orifices are separate but still close together, in M. michaelseni at some little distance apart; finally in M. modestus, as I have an opportunity for stating here, the pore of the sperm-duct is positively in the next segment to that which contains the orifice of the spermiducal gland. Nor do I admit that the approximation of the ventral setae in the genital segments is a character of sufficient importance to imply generic distinction. To begin with, M. diversicolor is somewhat intermediate, the approximation being less marked. Then the species of the genus are not all of them furnished with distant setae; in a good many of the South-American species the setae are strictly paired; this difference is itself of greater importance, I think; and the close pairing of the ventral setae in the neighbourhood of the male pores is an intermediate condition between the paired setae and the distant setae. If it is thought necessary to divide what I here call Microscolex into two genera, a more suitable line of division, as it appears to m e, would be to separate off those species in which the testes and sperm-duct funnels are only one pair ; this division would include all the new species described in the present paper with the addition of Microscolex spatulifer, and would include all the South-American forms, excepting only M. dubius and M. modestus. I do not, however, propose even this division of the genus. Most of the new species differ from Microscolex modestus and M. dubius, the types of the genus, in having a prostomium which entirely divides the buccal segment, and in that the setae are strictly paired. As, however, these two characters are not always correlated, I do not think it possible to create any new genera. Another interesting feature about some of the new species of Microscolex is that, like M. spatulifer and many of the Acanthodrilus, they are very brightly coloured. The internal structure does not present much of great interest. Indeed, the uniformity of the Cryptodrilidae as a whole is in striking contrast to the greatly varied structure of the Eudrilidae, with which I do not think that anybody now would venture to associate them. (1) Microscolex griseus, n. sp. This species, like Microscolex spatulifer, is one to which the generic name Microscolex is etymologically inapplicable. It is a large species, nearly if not quite as large as Microscolex spatulifer. |