GENUS DIPLOMASTIX. 433 



such permanently visible aperture. According to this last-named authority this type 

 would seem also to possess the same predatory habits as Cienkowski's monoflagellate 

 genus Colpodelia, he in certain of his figures representing examples extracting and 

 swallowing the nutrient protoplasm of a species of C/i/amydomonas, while in another 

 instance as many as eight animalcules have flistened to and are feasting, like so many 

 rats, upon the body of a large Colpoda cucullulus. The example figured by Stein 

 as illustrating one zooid preying in a similar manner upon another individual 

 of its own species, is evidently a misinterpretation of the first stage of coalescence 

 or genetic union, in which, as frequently observed by the author, see PI. XXIV. 

 Fig. 4, one animalcule fixes itself by its rostrum to the dorsal region of its selected 

 mate, the substance of the two becoming gradually amalgamated. Although 

 obtained in hay-infusions simultaneously prepared from both salt and fresh water, 

 it was found by the author to develop far more abundantly in the latter medium. 



Diplomastix caudata may be said to be one of the most ubiquitous repre- 

 sentatives of the Flagellate series, it putting in its appearance wherever decaying 

 organic matter, animal or vegetable, may be found. 



Diplomastix affinis, S. K. Pl. XXIV. Fig. 13. 



Body gibbously ovate, the posterior extremity rounded, or pointed and 

 bent towards the ventral aspect, the anterior end rostrate and recurved in 

 the same direction ; flagella of uniform size, slender, exceeding the body in 

 length ; contractile vesicle single, posteriorly situated ; endoplast spherical, 

 subcentral. Length 1-1500" to 1-1200". 



Hab. — Hay-infusions in salt and fresh water. 



The smaller size, persistent ventral curvature of the posterior extremity, and 

 location of the contractile vesicle, serve to distinguish this species from the 

 preceding, to which may be added the still more easily recognized and distinct 

 mode of locomotion. In D. caudata this, as already described, consists chiefly 

 of progress through the water in a straight line for a considerable distance, accom- 

 panied by a peculiar vacillating or hitching gait ; a similar vacillating action is 

 noticeable in the present type, but the animalcule never maintains its straight course 

 for a long distance, it bringing itself up suddenly and with a jerking motion every 

 few seconds through the adhesion of the trailing flagellum or gubernaculum, and 

 then starting oft", like a ship tacking, in a diflerent direction. Frequently also it 

 remains anchored by its gubernaculum, and fishes steadily with its extended anterior 

 flagellum or tractellum after the manner of an ordinary Heteromita or Anisojiema. 

 This sedentary phase has not so far been observed in D. caudata. Develop- 

 mental phenomena similar to those recorded of the last-named species were observed 

 of the present type, and it was further found that it multiplied with equal rapidity 

 in hay-infusions in both fresh and salt water. 



Diplomastix saltans, Ehr. sp. Pl. XXIV. Figs, ii and 12, 

 Body irregularly ovate, rounded posteriorly, with a convex dorsal and 

 concave ventral surface, the anterior extremity pointed, more or less curved, 

 often presenting a notched or bilabiate aspect ; the trailing appendage, or 

 gubernaculum, longer and stouter than the vibratile flagellum, or tractellum, 

 nearly twice the length of the body, the two inserted at some little distance 

 from the anterior extremity ; contractile vesicles two in number, anteriorly 

 situated ; endoplast subcentral. Length 1-1600" to 1-900". 

 Hab. — Vegetable infusions. 



This species is distinguished from the preceding by the notched or bilabiate 

 contour of the anterior extremity and by the more posterior insertion of the flagella. 



2 F 



