436 ORDER FLAGELLATA-EUSTOMATA. 



two large ovate germ-masses, modified apparently from a single pre-existing endo- 

 plast. Illustrations of these special features as observed by Stein are reproduced 

 at Figs. 28 and 29 of the accompanying plate. This more complex modification of 

 the contractile vesicle, while of rare occurrence among the Flagellata, will be found 

 to recur repeatedly with the more highly differentiated Ciliata described in the 

 succeeding volume. 



Anisonema truncatum. Stein. Pl. XXIV. Figs. 24 and 25. 



Body elongate, obconical or subtriangular, vi^idest and truncate an- 

 teriorly, tapering gradually towards the posterior extremity, rather over 

 twice as long as broad ; trailing flagellum about twice the length of the 

 body, the vibratile one slender, not one-half as long as the preceding ; paren- 

 chyma coarsely granular ; contractile vesicle situated close to the termina- 

 tion of the short, tubular pharynx ; endoplast elongate ovate, located 

 posteriorly near the left lateral border. Length 1-600". 



Hab. — Fresh water. 



Anisonema ludibundum, S. K. Pl. XXIV. Figs. 35 and 36. 



Body elliptical, very slightly depressed, somewhat narrower, but rounded 

 at the anterior extremity, cuticular surface smooth ; parenchyma trans- 

 parent, granulate ; flagella equally slender, about one and a half times the 

 length of the body, inserted at some little distance from the anterior 

 extremity ; contractile vesicles two in number, located side by side above 

 the point of insertion of the flagella ; anal aperture distinct, postero- 

 terminal. Length 1-2500". Hab. — Vegetable infusions, gregarious. 



This species was obtained by the author in some abundance from a flower-vase 

 in wliich the plants had been left until their stems were in an advanced state of 

 decomposition. Viewed in profile the body is seen to be much thicker than either 

 of the preceding species, from which it also differs in its considerably smaller size, 

 in the possession of two conspicuous contractile vesicles, and in the more rear- 

 ward insertion of the flagella. A number of animalcules were generally found in 

 close proximity, attached by their gubernacula and vigorously fishing with their 

 extended anterior flagella or tractella. Ever and anon a single individual would, in 

 the course of its oscillations, come in contact with a neighbour, causing it to 

 rebound against its fellows, stimulating those also into abnormal action ; the whole 

 colony thus aroused would whirl about for some seconds, apparently in sport with each 

 other, and in a manner comparable to flies playing, or to that recorded further on 

 of the Ciliate type Cydidiiun glancmn. Effete granular matter was distinctly 

 observed passing out at the posterior extremity of one of the zooids, as shown 

 at Pl. XXIV. Fig. 35. 



Anisonema intermedium, S. K. Pl. XXIV. Figs. 37-39. 



Body oval, depressed, slightly narrower anteriorly, surface smooth ; in 

 lateral view thicker posteriorly, and gradually narrowing towards the 

 anterior end ; the ventral surface flat or slightly concave ; flagella inserted 

 close to the anterior extremity, equally slender, about twice the length of 

 the body. Length 1-2000". Hab. — Sea water. 



The contour of this animalcule as seen in profile, together with its minute size 

 and salt-water habitat, appears to justify its recognition as a distinct species. A 



