OCR Text |
Show 218 MR. F. E. BEDDARD ON AN [Mar. 5, more like those of the Tubificidae, in which family these structures are very general. In the present species of Alma the spermatophores (text-fig. 59, B ) are dotted about irregularly, but always in front of the clitellar segments. The largest number that I observed were possessed by the most fully mature individual, which had nine of these bodies. They are roundish in outline and very flattened ; naturally they are firmly adherent to the integument. These two conditions must be very favourable to an earthworm having to force its way through the ground. It would be difficult to detach the spermatophores-more difficult one might imagine than in many Lumbricidae, where the cases stand out far from the body. The spermatophores have a thin wall, and the contents are exceedingly striking on account of their chalk-white colour. On a microscopical examination, the contour of the spermatophores is seen to be not perfectly circular; the margins are crenated, the bulgings being due to the abundance of the sperm. As it is a daugerous proceeding to argue from negative facts, I shall not do more than call attention to the fact that up to the present Criodrilus, justly placed by Michaelsen in the immediate neighbourhood of Alma, is the only Geoscolecid in which these structures have been hitherto made known. One matter, however, which may be emphasised is that, on the whole, the spermatophores of Alma resemble those of the Lumbricidae ; they are at least more like those of the Lumbricidae than of other Oligochaeta (save of course Criodrilus), though possessing distinctive features of their own. N o w there has been, since recent discovery, little doubt that among the Lumbricidae the spermatophores are a product of the tumid lips of the male pore. The suggestion was due to Eosa, who added that in earthworms which copulate in reversed positions the spermatophores are to be found behind the male pores. As a matter of fact this position is by no means constant; and in the species of Alma which I describe here they are both in front of and behind the male pores. As, however, Alma has no spermathecae it is clear that the spermatophores cannot be a product of the spermathecae as has been held ; there are, however (see below), tubercula pubertatis which might by their presence confirm the theory of origin for the spermatophores propounded by Fraisse. The flatness and slightly protruding spermatophores of this species are in accord with the very slightly prominent male pores. It seems to be hardly a question now but that the spermatophores are formed by the glandular cells which accompany the external orifice of the sperm-duct. Some other Anatomical Features.-I was myself disposed at one time to think that but one species of the genus Alma had been properly defined. I am now of the opinion of Michaelsen, expressed in his latest work (9), that four forms can be recognized. These species all come from different parts of Africa, with the exception of A. emini and A. stuhlmanni, which are associated together at Bukoba, Lake Victoria Nyanza. As the species which I describe here was obtained from a locality about fifteen hundred |