144 PROCEEDIN'GS OF THE ACADEMY OF [PaRT i 



is in question, or a particular variety, but the facts are not clear 

 enough to allow any definite conclusion. 



Cryptomonas ovata Ehrenberg. Plate VIII, figures 55-57. 



Pascher, on page 105 of the second fascicle of his "Siisswasser- 

 Flora," accompanies the diagnosis of the genus Cryptomonas with 

 the following reflections: "A very widely distributed genus, that 

 sometimes forms "water-flowers" (Wasserbliiten) and is frequently 

 associated with Euglenae ; is particularly frecjuent in water rich in 

 organic substances and in sewer refuse. Nearly all of the forms 

 are also planktonic. Only few of them are known, and an exact 

 study would furnish with a swarm of species." In a note at the 

 foot of the page, Pascher adds: "I hope to give within two years a 

 detailed monograph of the freshwater Cryptomonadinae." To my 

 knowledge, the work has not been published yet, and any informa- 

 tion about this interesting, somewhat paradoxal little group, might 

 have its importance. 



Cryptomonas is indeed found everjrwhere, but most of my 

 observations, dating from 1916, have been made on specimens from 

 that same marsh at Pinchat of which mention has so often been 

 made; later on, in January, 1917, a collection was studied from 

 another station, Rouelbeau, where individuals were found at rest, 

 enclosed in a gelatinous envelope, and often in course of division; 

 and lastly," in December, 1918, a special form from a pond at 

 Florissant, in the near neighborhood of Geneva, was studied again. 

 In all these different stations, the species was the same^the same, 

 at least, after determination by means of the keys in "Siisswasser- 

 Flora" — namely, Cryptomonas ovata; but such was the difference 

 between the forms of Pinchat and Rouelbeau on one side and Floris- 

 sant on the other, that one might ask if it was right indeed to re- 

 unite finally Ehrenberg's two species ovata and curvata into one 

 (ovata) . The Pinchat-Rouelbeau type was in fact Crypt, ovata (with 

 the variety curvata Lemmermann), and the Florissant type was the 

 genuine Crypt, curvata Ehrenberg. 



Ehrenberg, on page 41 of his classical work (''Infusionsthier- 

 chen"), gives the following diagnosis of Cryptomonas ovata: "Monad 

 with an oval carapace, with compressed body, oval, large, twice 

 as long as broad, 2V millimeter in length, color green." Pascher 

 (Stisswasserflora, p. 105), in his diagnosis of the genus, describes 

 the general appearance in more precise terms: "Cell typically show- 

 ing dorso-ventral differentiation, with generally a more flattened 

 or even somewhat concave ventral side and often a highly convex 



