372 



B e d dai (1 takes up rather a curious position in regard to the pro- 

 state of il/o«e7i^aA^e/'. For him, the peritoneal coat, outside the mus- 

 cular wall of the atrium is the «prostate« , and is homologous with the 

 »Cementdriise« (or prostate) of Tuhifex. 



Now, this prostate in Tuhifex, has heen shewn by Vejdovsky, 

 to be formed by a proliferation and outgrowth of the atrial epithelium 

 at a certain point, which bursts through the muscular wall of the 

 atrium and projects into the body cavity. The atrial epithelium is 

 derived from the epidermis, so that the »Cementdriise« is epiblastic. 

 Where as the glandular covering of the »atrium« of Moniligaster, 

 Sty larici, Rhynchelmis Sec. is mesoblastic — if it is in reality a modi- 

 fication of peritoneal cells. Hence, Beddard would regard the epi- 

 blastic »prostate« (Cementdriise) of Tuhifex as the homologue of the 

 mesoblastic covering of the atrium oî MoniligasterW 



It appears to me that, if this layer of cells in Motiiligaster, Stylaria 

 and other genera is really not surrounded by another layer of cells, 

 but is itself peritoneal, then there Avill be no secretion passed into the 

 atrium. Is there any known case of coelomic epithelium being converted 

 into a gland which pours its secretion to the exterior? From Beddard's 

 and Vejdovsky's drawings these cells appear very similar to the 

 chloragogic cells surrounding the intestine and dorsal blood vessels in 

 Lumhricus and other Oligochaeta. These cells have no communication 

 with the intestine and do not merit the term »hepatic cells« which has 

 sometimes been given to them. They have no function in relation to 

 digestion, and I believe that the same is true in the case of the so- 

 called «prostate« (Beddard) oi Motiiligaster"^. 



University College, London, April 27. 1890. 



7. Notizen über die pelagische Thierwelt der Seen in Kärnthen 

 und in der Kraln. 



Von Dr. Othm. Em. Imhof. 



(Schluß.) 



eingeg. 5. Mai 1890. 



14. St. Leon hard -See. 



Protozoa: Flagellata: Dinohryon diver gens Imh. 



Dinoflagellata : Ceratium hirundinella O. F. Müller 



Peridinium tahulatum Clap. Lach. 



2 I may state, in regard to Rhynchelmis, which possesses a similar layer of cells 

 outside the muscular coat of the atrium, that I can detect in sections a delicate 

 membrane surrounding the pear-shaped cells — Mhieh is no doubt the true coelomic 

 epithelium. 



