OCR Text |
Show 1892.] NEW SPECIES OF EARTHWORMS. 141 spheres, and younger stages in the development of spermatozoa, though their position in this somite is rather diffcult to explain, except on the idea that the septa, here delicate, may have become ruptured or displaced in dissection. But Perrier was a very careful dissector, and he had had great experience in the dissection of Earthworms, so that it is scarcely justifiable to suggest a mistake in the matter. In P. perrieri there are four pairs of spermathecae lying in somites vi. to ix.; each is an ovoid sac, without any distinct neck or duct and without a diverticulum (Plate VII. fig. 3, spth.). Each sac opens at the anterior margin of its somite-practically intersegmental^- in a line with the second chaetae. [In P. heteroporus there are five pairs, the additional pair being in somite v.; each sac has a diverticulum.] I may add that in the genus Perichceta we find species with and species without diverticula to the spermathecae. In the alimentary tract the position of the gizzard is to be noted ; it lies, as seen in sections, entirely in somite v., though its hinder extremity is carried back to the level of somite ix. (Plate VII. fig. 3, giz.). The following region of the gut, as far back as somite xvi., has very vascular walls, which are considerably folded (Plate VII. fig. 3). But there are no definite " pouches" or diverticula, though the general structure recalls that of calciferous glands ; and I find in the hinder somites crystalline bodies, resembling those of carbonate of lime present in the glands of Lumbricus, but there is no effervescence on the application of acetic acid. This vascular region of the gut is not so extensive as it appears on paper, for the cavities of somites vi., vii., viii. are exceedingly short, the septa being almost in contact centrally. The thin-walled intestine commences in somite xvii. or xviii. and is very wide, occupying a considerable extent of the body-cavity; there is no typhlosole (Plate VII. fig. 4). [In P. heteroporus the gizzard is in somite vii. ; there are three pairs of reniform diverticula, with short ducts, in somites x., xi., xii.] B. MlCROCHiETA PAPILLATA, n. Sp. W e are acquainted with only two species1 of this genus, which was instituted by Beddard2 for a worm originally described by Bapp under the name of " Lumbricus microchceta," collected in Cape Colony. Mr. Beddard named the species M. rappi, and it received a description at my hands3 almost simultaneously with that published by him. I described the second species, from Natal, under the name of M. beddardii. In a recent paper' I have pointed 1 After the M S . of this paper had left m y hands, I received from Dr. D. Rosa a copy of his memoir, "Die exotischen Terricolen des k. k. Naturhis-torischen Hofmuseums," published in the ' Annalen d. k,-k. Nat. Hofmuseums,' Wien, 1891, Bd. vi. Heft. 3 & 4. Herein he describes a third species, M. benhami. 2 Trans. Zool. Soc. xii. 1886, p. 63. 3 Q. J. M. Sc. vol. xxvi. p. 267. 4 Ibid, xxvii. p. 77. 5 "An Attempt to Classify Earthworms," ibid. xxxi. p. 215. |