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Show 1895.] ME. F. E. BEDDAED ON NEW EAETHWOBMS. 233 with the genus, in the xiith segment. The testes are large and bushy ; there are only a single pair of them lying in segment x. Opposite the testes are the conspicuous funnels of the sperm-ducts. I could find neither testes nor funnels in segment xi., where, however, are a pair of large and racemose sperm-sacs. The spermiducal glands are plainly separable into a glandular and a non-glandular portion. The latter is rather less than one-half of the length of the former and very much more slender. The entire gland is straight and occupies about four segments. It opens in common with an opaque thick-walled sac containing penial setae. This sac is not so long as, but much stouter than, the muscular end of the spermiducal gland. The sac-contained, in a specimen dissected by me, 8 penial setae on one side of the body. Only two of these, however, appeared to be fully mature. These were to be distinguished from the rest by the fact that the implanted end was curved. In the others this end was broadened out. In the former setae the free end of the seta tapering gradually to the end was unornamented ; in another specimen, however, these setae were faintly ornamented. I am therefore disposed to think that the ornamentation upon the immature setae is a mark of their immaturity, the spines being as a rule worn off in the setae which happen to be in use. A curious difference in the constitution of the two kinds of setae was shown by treating them with a strong solution of potash : when this reagent was applied, the presumably immature setae became almost invisible, while the others did not exhibit any changes. There is nothing worthy of comment concerning the ovaries and their ducts. The spermathecae are a single pair lying in segment viii. They are oval pouches, each with two symmetrically arranged diverticula, in which alone there appeared to be sperm. The spermathecae are precisely like those of Acanthodrilus bovei. In the gatherings from Punta Arenas and Uschuia, I found specimens coexisting with the normal form which were shorter (50 mm., 95 segments), and had a single median papilla upon segment xvii. instead of a pair. One specimen, however, had the two pairs of papillae characteristic of the typical variety ; hence I do not separate them as species. Hab. St. 75, Magellan Straits, Punta Arenas. St. 140, Uschuia, forest. St. 65, Magellan Straits, fresh water. St. 179, Navarin Isl., Porto Toro. St. 165, Puerto bridges. The resemblance between this species and Acanthodrilus bovei, coupled with their occurrence in the same locality, is interesting. This resemblance extends to internal characters. The spermathecae are similar in both, and in both the intestine begins unusually early, the xviith being the more usual segment. I call attention in the course of this paper to the likeness, more or less pronounced, between other species of Microscolex and other species of Acanthodrilus. Apart from these particular likenesses, it is a curious and not wholly intelligible fact that the bulk of the South-American |