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Show 1892.] OF THE G E N U S PERICHCETA. 161 single row present at the posterior boundary of the clitellar region, which belong therefore to segment xvi. ; it is at this point that the thick clitellar epithelium ceases. The setae do not form a continuous ring round that segment (the xvith) ; they are visible only upon the ventral surface and are developed for an equal distance on either side of the ventral median line ; they extend for a distance of about one quarter of the entire circumference of the segment. The clitellar setae are quite obvious without having recourse to a microscopical investigation of the integument, since the thick clitellar epithelium is much broken along the line of their emergence. The setae themselves do not appear to present any differences in shape from those which are found in other parts of the body; they may perhaps be a trifle smaller, but there is no such differentiation as occurs, for example, in Perichceta houlleti. The most careful search failed to show any setae on either of the two remaining segments of the clitellum : in one specimen I counted 20 setae on segment xvi.; in another there seemed to be rather fewer, but there was no perceptible variation in the length of the line occupied by the setae in different individuals. I have been particular in calling attention to the characteristics of the clitellum, not only because the points to which I have directed attention are of specific importance, but also for the special reason that they serve to discriminate Perichceta bermudensis from Perichceta aspergillum. I was at first inclined to regard the species described in this paper under the name of Perichceta bermudensis as being identical with Perichazta aspergillum. The latter was first described by Perrier1 as being "sans designation d'origine." As I received a few years ago some Earthworms collected by Mr. Shipley in the Bermudas which seemed to be P. aspergillum, I considered that the present species was the same, as the individuals agreed, on a superficial inspection, with Perichceta aspergillum. However, in Perrier's description of P. aspergillum there are characters mentioned which appear to show that I am right in regarding Perichceta bermudensis as a distinct though closely allied form ; in the figure 2 illustrating Perichceta aspergillum setae are figured upon all the segments of the clitellum ; but in the text the matter is left a little obscure. M . Perrier says (p. 120), " Je n'ai v u sur la ceinture que de faibles traces . . . . des ceintures de soies." The great difference in size m a y possibly also be a valid specific difference ; no doubt this character is one which has to be used with special caution in the case of Earthworms. There are other points, too, which I shall call attention to in referring to the characters offered by the male generative pores and the spermathecal pores. The dorsal pores commence, as in Perichceta aspergillum, between segments x./xi. The oviducal pore lies upon the middle ventral line of segment xiv. 1 "Recherches pour servir a l'histoire des Lombriciens terrestres," Nouv. Arch. Mus. t. viii. p. 5. 2 Loc. cit. pi. iy. fig. 71. PROC. ZOOL. Soc-1892, NTo. XI. 11 |