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Show 1899.] ON TWO EARTHWORMS. 805 The clitellum itself seems not to occupy quite fully the first and the last of its three segments. The second characteristic feature of thi:* species is the arrangement and the numbers of the genital papillae. These papillae are paired and follow the 28th segment. The greatest number of pairs found in our examples was 5 ; the following numbers were also observed : 4 pairs, 3 pairs; 5 right side 4 left, 3 right 4 left, 4 right 3 left, 4 right 6 left. Perrier found as many as 7 pairs; Michaelsen not more than 5, as was the case with us. This asymmetry of the genital papillae, which is not by any means a novelty any more than is the varying number of pairs in individuals, is coupled with an irregularity and asymmetry of the spermathecae. It is mainly upon this matter that we desire to lay stress in the present communication. In first of all describing the species Perichceta acystis the author recorded, without commenting upon the fact, that papillae were also present. N o w in species without spermathecae there are, as a rule, no papillae. Not many examples occur among earthworms of species which are without these characteristic Oligochaetous organs ; but there are a few, among them being two species of the present genus. Dr. Rosa * has described Perichceta aiheca, and Dr. Michael-sen 2 Perichceta barami. In the first mentioned there are no genital papillae; in two individuals of the latter the papillae were reduced or absent. In species of Allolobophora, on the other hand, there are no spermathecae, such as A. eiseni, there are also no tubercula pubertatis. Of Perichceta aiheca. Rosa examined several individuals, so that there the coincidence of absent genital papillae and missing spermathecae seems to be absolute. In Perichceta biserialis, on the other hand, spermathecae are sometimes absent and sometimes present. Perrier makes no mention of the matter at all in his brief account of the species. Michaelsen bad five examples, all of which possessed two pairs of these organs in segments vi. and vii.; the number of genital papillae varied, as already said. The two specimens which formed the material upou which the species Perichceta acystis was established had each five pairs of genital papillae and no spermathecae. In the present collection there are 12 specimens without and 6 with spermathecae; but no ascertainable relation exists between the condition of the papillae and that of the spermathecae. W e may fairly put aside Perichceta aiheca for two reasons. In the first place, it may still be that the species is, like P. biserialis, sometimes with and sometimes without spermathecae, and also for the reason that an absence of genital papillae is so general or at least so common among Perichceta that it need have no significance in connection with the absence of spermatheca**. The absence, then, of any connection between 1 " I Lombrichi raceolti a Sumatra dal doit. Elio Modigliani," Ann. Mus. Civ. Genova. xxxvi. p. 520. 2 Oligochaeten : from Kiikenthal," Ergebnisse einer zoologischen Forschungs-reise in den Molukken und in Borneo," Abh. Senck. nat. Ges. xxiii. p. 203. PROC. ZOOL. Soc-1899, No. LII. 52 |