OCR Text |
Show 1887.] ANATOMY OF EARTHWORMS. 545 arrangement of these papillae there is really some little difference between the two species. In the first place, C. rusticus has only four of these dumbbell-shaped papillae, while there are five in my specimen ; this is a difference which might easily be explained away on the assumption that Fletcher's specimens were immature, except for the fact that he has examined a large number. Secondly, the papillae in C. fletcheri are restricted each to one segment, the whole of the ventral area of which they occupy ; in C. rusticus, on the other hand, the papillae appear to be intersegmental in position. The male generative pores are upon the eighteenth segment and are placed within the area of the ventral papillae close to the pair of setae. The female generative pore is situated upon the fourteenth segment; it is a single slit-like orifice with tumid lips. The apertures of the spermatheca as well as those of the nephridia were invisible in my specimen. The seta appear to have the same arrangement as in C. rusticus, viz. a pair of setas on either side of the ventral line moderately close together and a laterally placed pair, the individual setae of which are wide apart *. The following notes upon the internal anatomy of the species are of course no more than is necessary for its adequate definition. I hope to be able at some future time to work out more elaborately certain points in the structure of this and other Lumbricidae. Alimentary Canal. The chief feature in the anatomy of the alimentary canal to which I may call attention is the presence of calciferous glands ; as these glands appear occasionally to be absent in Earthworms, it is important to record their presence in this species. I noticed two pairs of calciferous glands situated in segments 11 and 12; there may have been others, but an accident prevented an examination of the posterior segments. The position of the glands is somewhat unusual; instead of lying to the side of the intestine as is generally the case (e. g. Acanthodrilus, P. Z. S. 1885, pl. Iii. fig. 1), they are placed below the intestine, and each gland comes into close relations with its fellow, separated from it, however, by the subintestinal vessel, which is supported by a mesentery. The gizzard occupies segments 6 and 7. Nephridia. Another structural feature of this Earthworm renders it quite impossible to confuse it with Cryptodrilus rusticus, or, for the matter of that, with any other of the Australian species of Lumbricidae. Mr. Fletcher speaks of the nephridia as consisting of dendriform masses or tufts of glandular caecal tubes, more developed in the 1 Since this portion of m y paper was written Mr. Fletcher has described (Proc. Linn. Soc. JN. S. W., Sept. 1886) a second species of Cryptodrilus (C. saccarius), which cannot be confounded with the species described above. It agrees with C. rusticus in the characters of the nephridia. |