1893.] ox THE ATBIUM A^D PROSTATE IX THE OLIGOCH.ETA. 475 



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

 after very heavy rains, which are not of very frequent occurrence. 

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

 and the Diprotodon remains are somewhere about mid^^•ay bet\^eeu 

 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 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. 

 We have, for instance, remains of Alligators or Crocodiles from a 

 district not far oif, and other evidence of freshwater-life. Of 

 course we are on the look-out for Thi/lacoU'o ; but, so far, it does 

 not appear to have been met with ; but I am quite hopeful that if 

 we can ni:inage 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 wTiting far into the night so as to catch the mail to-morrow. 



"E. C. S." 



The follow ing papers were read : — 



1. Ou the Atrium and Prostate in the OligodiEeta. By 

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

 Society. 



[Received May 2, 1893.] 



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

 Ohgochaeta 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 Tubificidtc and 

 Lumbriculidte; " prostate " has been the term usually ap])lied to 

 the glandular structures in Earthworms which aroap])ended to the 

 male duct. The latter term was first applied by Vaillant (1, who 

 first described a worm with the glands in question, viz. Periihata 

 jjostjwma), who remarked concerning the gland : " faut il y voir une 

 vosicule seminale accessoire ou une glande annexe comparable k 

 une prostate?" Th(i word "atrium" appears to liavc; been first 

 used by Claparcde (2, p. 21) in the case of Tidnfc.r. Vaillant was 

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

 in Perklunta were siii (/enn-is and not comparable to any structures 

 in other Oligoclia^ta. Vejdovsky is the first writer who has 

 attempted any comparison between the structures in question 



