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Show 1901.] ANNELID OF THE GENUS AEMA. 217 to be usually the case with full-grown terrestrial forms. And in this connection it should be borne in mind that Alma is very largely an aquatic genus itself. Clitellum.-TheGeoscolicidae agree with theLumbricidae, to which they are clearly very closely related, in the fact that the clitellum is often placed very far back in the body. Such a position is especially characteristic of the Madagascar genus Kynotus, in four species of which the clitellum commences at the xixth to the xxist segment. There is, however, n * Geosolecid where the clitellum commences at a point farther back than the xxiind segment; Glyphidrilus stuhlmanni has a clitellum which commences at this segment. On the other hand, in the Lumbricidae the clitellum is as a rule much farther back than in the Geoscolicidae, commencing as a rule at a segment between xxii. and xxx. It is to this family that Alma shows the greatest likeness. In the specimen before m e the clitellum (text-fig. 59, CI.) is exceedingly plain on account of the white and opaque appearance of the integument; the individual segments which are comprised within the clitellum are, however, perfectly distinct, their lines of division not having been obliterated by the glandular modification of the skin. The clitellum does not commence or end at all sharply. The first segment which is fully modified is segment xlvii.; but two or three segments in front of this are slightly invaded by glandular tissue aud in an irregular fashion. It is possible therefore that in a more fully mature example the clitellum would be found to have a greater extent than even the very large one which I record here. The last segment of the clitellum which is completely modified is segment lxxxii.; but here again two or three segments after this one are slightly modified. W e may regard it as extending from xlv.-lxxxv. The clitellum, where fully developed, is continuous right round the body. This position of the clitellum is, however, much farther back than is the case with the large majority of the Lumbricidae. There are, indeed, only four species where it commences at or just before the xlth segment. In Allolobophora robusta the clitellum extends from xl.-lxii.; in A. molleri from xlviii.-lix.; in A. moebii from lii.-lxii. Lumbricus polyphemus has a clitellum which reaches from xxxix.- xliv. It will be observed therefore that Alma is very exceptional in the backward position of this region of the integument, and that in extent coupled with position it is quite unique among earthworms. Spermatophores.-The existence of these structures can be affirmed for the Lumbricidae and for Criodrilus and Polytoreutus alone among the earthworms. As regards the former family, de Eibaucourt has recently added so much to our knowledge of those species among the genera Lumbricus and Allolobophora which possess spermatophores (10), that his conclusion that their existence will prove to be nearly if not quite universal for the family seems to be reasonable. The spermatophores of Criodrilus are much like those of the Lumbricidae. Those of Polytoreidus on the other hand, described by myself, are of a different pattern, and on the whole |