3 I 2 ORDER FLA CELL A TA -PANTOS TO MA TA . 



ascertain the respective thermal death-points of the adult monad and its spores, 

 elicited that the former succumbed at a fluid temperature of 142 Fahr., while the 

 spores successfully resisted the very considerable one of 220 Fahr. of fluid heat, and 

 the still higher one of 248 Fahr. if submitted to dry heat. 



GENUS IV. TRIMASTIX, S. K. 

 (Greek, treis, three ; mastix, lash.) 



Animalcules naked, entirely free-swimming, more or less ovate or 

 pyriform, with a laterally produced membranous border ; flagella three in 

 number, anteriorly inserted, one vibratile directed in advance, two reflected 

 and trailing posteriorly ; endoplast and contractile vesicle conspicuous ; no 

 distinct oral aperture. 



, Trimastix marina, S. K. PL. XIX. FIGS. 24-26. 



Body subpyriform, rounded and inflated posteriorly, the pointed and 

 attenuate anterior extremity curved slightly towards the ventral aspect ; the 

 lateral border produced on the right-hand side, extending from the anterior 

 to the posterior extremity; flagella subequal in size and character, about twice 

 the length of the body, the anteriorly directed flagellum vibratile throughout 

 its length, one of the reflected ones free, the other retained towards its 

 centre by the angle formed between the body-wall and lateral membrane, 

 its length between this region and its point of insertion at the apical extre- 

 mity constantly vibratile ; contractile vesicle anteriorly located ; endoplast 

 spherical, adjacent to the posterior extremity. Length 1-1425". 



HAB. Salt water with decaying vegetation. 



This species was obtained by the author in November 1878, at St. Heliers, 

 Jersey, in a vessel of sea-water containing Fuel in an advanced state of decomposi- 

 tion, a thick Bacterial pellicle in the gelatinous or "zooglcea" condition being 

 present on the surface. While the general form, number, and disposition of the 

 *' flagella correspond to some extent with those of Dallingeria, it differs conspicuously 

 from that and all other types hitherto described in the development of the 

 remarkable lateral border, and in the peculiar comportment of one of the posteriorly 

 reflected flagella with relation to it. As first seen, it was premised that the anterior 

 portion of this appendage was an independent undulating membrane, analogous 

 to that possessed by Trypanosoma or Trichomonas, but its continuity with the 

 portion produced beyond the posterior extremity was ultimately traced. The 

 membranous lateral border, imparting to the animalcule a scroll-like aspect, or more 

 correctly, perhaps, that of a convoluted shell, is of comparatively firm consistence, 

 and was not observed to exhibit any variation in its contour. Although not repre- 

 sented in any previously known member of the Flagellata, a somewhat similar 

 lateral membranous expansion occurs in the Holotrichous forms Lembus and Probo- 

 scdla. It was supposed that the vibratile portion of the reflected flagellum might be 

 connected with the office of conducting food-particles to a distinct oral aperture. 

 No such orifice, however, was observed, nor the inception of food-substances at 

 any part of the periphery. 



Fam. XV. TETRAMITID-ffi, S. K. 



Animalcules naked, entirely free-swimming ; flagella usually four, 

 rarely five, in number, inserted close to one another, near the centre of the 

 anterior border ; no distinct oral aperture. 



