OCR Text |
Show 1892.] NEW SPECIES OF EARTHWORMS. 147 one pair in somite ix.-one somite anterior to that of M. rappi. In M. beddardi, however, the gland is partly in somite ix. and partly in somite x., occupying, as it were, an intermediate position between that of the other two species. The genital organs.-There are apparently three pairs of sperm-sacs, but in reality only two pairs are present, each sac being constricted into a larger anterior portion, and a small posterior and more ventrally situated lobe. The two larger sacs (Plate VIII. fig. 13, A, B) lie in somites x. and xi.; the posterior lobes, constricted by the septa, lie in somites xi. and xii. (C, D). There are no mediau sacs. The two pairs of testes and of ciliated rosettes, which lie in somites x. and xi., are enclosed in the larger portions of the sacs. In M. rappi there is the same kind of subdivision of the sperm-sacs, the anterior lobe, however, of each being the smaller and containing the testes; they occupy (according to the amended numbering of the somites) the same position as in the present species. The two sperm-ducts of one side unite in somite xii., but I was unable to trace them onwards; they have no connection with either of the copulatory apparatus mentioned above. The spermathecce have the same arrangement as in the other species ; that is, a row of ten or twelve very small oval sacs on the anterior margin of each side of somites xiii. and xiv. In M. rappi there are fewer in each row, but four rows on each side, and some of them are curved. Similar spermathecae exist in Brachydrilus 1 and in Kynotus. C. MICROCHCETA BELLI, n. sp. This species agrees in its anatomy very closely with M. beddardi, I name it after m y friend Prof. Jeffrey Bell, who has enabled me to examine and study a large number of Earthworms presented to the National Collection 2. Its length is 8 inches and its diameter is | inch. It had apparently been allowed to become dry at some period before it reached me, as the worm is much shrivelled, and a dark brown, hardened, plate-like structure occupies the dorsal surface of somites xiii. to xxi. and part of the next somite; this " saddle " extends laterally as far as the nephridiopores, or line of the outer chaetae. This brown area appears to represent the clitellum. Along the lateral boundary of part of the clitellum is a broadish band, having a glandular appearance, crossing the somites xv., xvi., xvii., xviii., and part of xix. This recalls the tubercula pubertatis of the Lum-briciclce, and a similar structure is already known in Rhinodrilus and Hormogaster, and Horst speaks of something of the sort in Glyphidrilus3. On the ventral surface these segments, though dis- 1 Benham, " An Attempt to Classify Earthworms," Q. J. M. Sc. xxxi. p. fig. 28. 2 The specimens of M. papillata and M. belli are now in the collection of the British Museum. 3 In M. benhami, Rosa, loc. cit. also describes tubercula pubertatis. 10* |