The Microscope. 



231 



on the sm-face of Vorticella monilata, giving the body a coarse, gran- 

 ular appearance, even under a low power. The ciliary disc is mod- 

 erately elevated, convex and tumid. Contractile 

 vesicles two in number, slowly and alternately pulsa- 

 ting. The endoplast is long, somewhat twisted, and 

 placed longitudinally. 



The pedicel dichotomously branched without 

 septa, few zooids in a colony. Length of body ^^ of 

 an inch. 



On Cambarus and plants, Scajaquada creek and 

 Niagara river. 



This is, I think, the only Carchesium thus far 

 observed with two contractile vacuoles, a character not 

 attributed to the Vorticellidse in the manuals, although 

 several species of Vorticella are now known to 

 possess two. One, V. vestita, occurs in the same locality as this species. 

 While it is easy to observe the two vesicles in some examples, I l^ave 

 not succeeded with others; my experience is similar with the Vorticella 

 mentioned. This does not prove that the second one is not there? 

 still I cannot help doubting that it is. Is then the possession of two 

 contractile vesicles by a vorticellid a peculiarity, or, when present, due 

 to a state or condition ? I am aware that the weight of evidence at 

 present is in favor of the constancy of the character, and when not 

 seen there is a fault in the observation. 



Opercularia huniiiis, n. s. (fig. 4.) Body fusiform, slightly gib- 

 bous, cuticular surface transversely striate under high magnification. 



Nucleus ribbon-like, bent into a U, 

 placed transversely. Contractile vesi- 

 cle low. Peristome border thickened 

 and slightly dilated. Lid narrow, 

 convex, moderately elevated. Cilia 

 ample. Membranous frill or collar 

 slightly elevated. 



When contracted, the body becomes 

 napiform with a snout-like projec- 

 tion. The plastic bodies are often 

 made to bend over sidewise until they 

 rest upon the supporting object. The 

 pedicel is extremely short, a mere nodule on which the four to eight 

 zooids are clustered. 



