1893.] OS THE ATEIUM -tN'D PROSTATE IN THE OLIGOCH^TA, 475 



level expanse of salt-encrusted, black mud, only becoming filled 

 after very beavy rains, wbicb are not of very fre(]uent occurrence. 

 Lake Mulligan is relatively small, being only about 8 miles across, 

 and the Dijjrotodon 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 im- 

 mense herd of these and other animals had got bogg;ed, 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. 

 We 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 rannage to prosecute the search, that tins 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 1 

 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 Oligocliseta. By 



Frank E. Beddard, M.A., F.R.S., Prosector to the 



Society. 



[Eeceived May 2, 1893.] 



The structures termed "atrium" and "prostate" in the 

 Oligochseta 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 Tubificidse 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 

 ])osthu7na), who remarked concerning the gland : " faut ily voirune 

 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 Tuhifex. Yaillant was 

 of opixiion that the glands, which he described for the first time, 

 in Perichceta were sui generis and not comparable to any structures 

 in other OhgochcEta. Vejdovsky is the first writer who has 

 attempted any comparison between the structures in question 



