140 Proceedings of the Royal Irish Academij. 



XIX. — On Chla]u:tdomtxa labteinthuloides, not. gen. et sp., A 

 New Feeshwatee Saecodic Oeganism. By William Aechee, 

 M. R. I. A. (With Plates 1 4 and 1 5 . ) 



[Eead February 22, 1875.] 



Some short time after the appearance of Cienkowski's memoir on a 

 new type of Sarcodic existences, met with by him in the sea (at 

 Odessa), which he named Labyrinthuleae, I was not a little surprised 

 and interested on meeting with a form from the freshwater so wonder- 

 fully resembling those described by him, as, notwithstanding one 

 circumstance, hereafter to be adverted to, even still to render it a 

 matter of considerable question whether it may not truly belong to 

 that group, even though it should not be congeneric with the typical 

 Labyrinthula (Cicnkowski).* 



I regret indeed that, after repeated efforts to learn more of its 

 development or history, I have but little succeeded, except so far as 

 knowing that it is an endoparasitic growth, at least for a portion of its 

 existence. 



It will, perhaps, be the best course to endeavour first to give an 

 idea of this curious production as it exists, before referring to 

 Cienkowski's forms, which would, indeed, be necessary previous to 

 comparing or contrasting it therewith, or with any other simple 

 organisms evincing any similarity in minute specialities. 



The component elements of the present form, broadly taken, are 

 primarily divisible into two — the inner soft sarcodic body-substance, or 

 contents, and the outer rigid cyst, or envelope, which nearly constantly 

 surrounds the former. 



But neither of these is quite simple, especially the latter, which 

 presents a variety of constituents. 



To advert briefly in the fii'st place to the latter, the outer coat or 

 envelope, its complexity consists, indeed, only in the number of similar 

 layers of which it is composed, and its great irregularity of outline. 

 It is often very thick, according to the numbeii of laminae of which it 

 is made up, but even the thinnest, or such as possess but a single lamina, 

 would, on the whole, be called "thick- walled" as compared with many 

 vegetable cells. This wall is hyaline, and when -viewed superficially it 

 is colourless, or nearly so, but when viewed edgeways or at the margin 

 of a many-laminated example, where a considerable density is therefore 

 seen through, it appears of a pale straw colour- or brassy hue, and ex- 

 tremely shiny and glossy. Its consistence is tough, requiring strong 



* Cienkowsld : " Ueber den Bau und die Entwickehmg der Labpinthuleen," 

 in Schultze's " Arcbiv fiir mikr. Anatomie," Bd. iii., p. 274. 



