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Show 146 DR. W. B. BENHAM ON [Feb. 16, definite spots, has taken the place of, or is developed in addition to, this clitellar sucking arrangement. It is very generally believed that in Lumbricus herculeus, Savigny (L. terrestris, auct.), a mucous band is developed around the bodies of the two worms during the process of copulation : but, from my own repeated observations of the act in Lumbricus, I can state, as some of the older authors have stated, that such a band does not exist. There is such a band in Allolobophora foetida and no doubt in other species, but in Lumbricus the two worms are joined together, and that pretty firmly, by the action of the tubercula pubertatis, and no doubt by a certain amount of sucking-action, exerted by the ventral region, not only of the clitellum, but also of all that part of the body lying between that and the fifteenth somite, which is converted into a groove by the action of a band of muscles passing from one side to the other-the arched muscles l. In worms, such as Perichceta and Acanthodrilus, &c, where the clitellum is "complete" or nearly so, and where no tubercula pubertatis exist, there is no evidence of any power of converting the ventral surface of the body into an adhesive apparatus : and it is in these forms that a (probably) protrusible penis-or muscular duct of the prostate-exists. This organ has either (1) actually replaced the adhesive arrangement such as exists in Lumbricus, in which case the sucking-papillae, independent of the sperm-duct in Microchceta and the (probably) similar apparatus around the male pore in Geoscolex, Brachydrilus, Criodrilus, may represent stages in the process ; or (2) the two modes of copulation may have arisen independently. The Internal Anatomy. In the arrangement of its internal organs M. papillata agrees closely with that of the previous species. The nephridia, though smaller, present the characteristic tuft of coiled tubules at the end of a fairly large bladder ; the " fine tube " 2 presents the same peculiar branching and anastomoses that I have described for M. rappi3. The dorsal blood-vessel is doubled in the somites v., vi., vii., viii., and ix., and in the last somite is dilated to form a double heartdike organ ; in each case the two vessels unite at each end of the somite to form a single tube perforating the septa ; in M. rappi this doubling occurs in the same somites, but in M. beddardi it is limited to somites vii., viii., and ix. Large moniliform " lateral heirts " exist in the present species in somites ix., x., xi., and smaller ones in somites vii. and viii., as in M. rappi. With regard to the alimentary tract, the chief features to be noted are (a) the gizzard, which appears to occupy somite vi., and (b) the oesophageal diverticula or calciferous glands ; of these there is but 1 Oerfontaine, "Rech. sur le Syst. cutane et sur le Syst. musculaire du Lomb terr.," Arch, de Biologie, x. 1890, pi. xii. fig. 26, p. 407. 2 " The Nephridium of Lumbricus," Q. J. M . Sc. xxxii. 3 Q. J.M. Sc. xxvi. pi. xvi. fig. 21, and pi. xvi. bis fig. 31. |