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Show 1893.] ON THE ATRIUM AND PROSTATE IN THE OLIGOCHJETA. 475 level expanse of salt-encrusted, black mud, only becoming after very heavy rains, which are not of very frequent occurrence. Lake Mulligan is relatively small, being only about 8 miles across, and the Biprotodon remains are somewhere about midway between the east and west edges. Usually the salt crust is not firm enough for bullock-traffic, and I may safely say that thousands of bullocks have at different times been bogged in crossing or attempting to cross .... The bones, as will be seen, lie close to the surface, that is two or three feet [beneath] .... It would appear that an immense herd of these and other animals had got bogged, probably in seeking water in a dry season, just as cattle do now in the North by hundreds. There is every indication that all this region of South Central Australia was formerly occupied by freshwater lakes. W e have, for instance, remains of Alligators or Crocodiles from a district not far off, and other evidence of freshwater-life. Of course we are on the look-out for Thylacoleo • but, so far, it does not appear to have been met with ; but I am quite hopeful that if we can manage to prosecute the search, that this and perhaps other remains will be met with. "This is about all the information I can give you at present. Again excuse its unsystematic and fragmentary character, but I am writing far into the night so as to catch the mail to-morrow. "E. C. S." The following papers were read :- 1. On the Atrium and Prostate in the Oligochaeta. By F R A N K E. B E D D A R D , M.A., F.R.S., Prosector to the Society. [Eeceived May 2, 1893.] The structures termed "atrium" and "prostate" in the Oligochaeta have given rise to considerable differences of opinion as to their nature. The word" atrium " has been generally used for the dilated chamber into which the sperm-duct opens in the Tubificidae and Lumbriculidae ; " prostate " has been the term usually applied to the glandular structures in Earthworms which are appended to the male duct. The latter term was first applied by Vaillant (1, who first described a worm with the glands in question, viz. Perichceta posthuma), who remarked concerning the gland : " faut il y voir une vesicule seminale accessoire ou une glande annexe comparable a une prostate ?" The word "atrium" appears to have been first used by Claparede (2, p. 21) in the case of Tubifex. Vaillant was of opinion that the glands, which he described for the first time, in Perichceta were sui generis and not comparable to any structures in other Oligochaeta.' Vejdovsky is the first writer who has attempted any comparison between the structures in question |