370 



ORDER FLA CELL A TA -E US TO MA TA . 



described, and with which, so far as external contour only is concerned, they in 

 many instances exhibit the closest possible correspondence. 



Genus I. PARAMONAS, S. K. 



(Greek, J>ar(7, close to ; monas.) 



Animalcules free-swimming, ovate or globular, uniflagellate, more or 

 less persistent in shape, incepting food-substances through a distinct oral 

 aperture which is situated anteriorly at the base of the flagellum. 



The above generic title is here instituted for the reception of several forms re- 

 ferred to the genus Monas by De Fromentel,* but which are declared by him to possess 

 a distinct oral aperture. A still larger number of the species hitherto relegated to 

 the same generic group will probably have to be transferred in a similar manner to 

 this present one, as soon as a more perfect knowledge of their minute struc- 

 ture and life-history shall have been gained. Owing to the greater density, though 

 not absolute rigidity, of their cuticular investment, the representatives of the 

 genus Faratftonas, in addition to possessing a distinct oral aperture, are further 

 characterized by their comparatively persistent shape. These features, taken 

 collectively, secure for them a distinction from the members of the genus Monas, 

 similar to that which is further on shown to subsist between the otherwise super- 

 ficially corresponding generic types Heteromita, Hdcronema, and Anisonema. The 

 genus Petalomonas of Stein, represented by the CycUdium abscissnm, and possibly 

 also the C. nothdosnni and C. crassuni of Dujardin, necessarily approaches most 

 closely to Paramonas. As, however, the flattened and leaf-like contour of the body 

 is insisted on as a leading characteristic of Stein's genus, it is requisite to establish 

 an independent one for the globular or ovate forms included under the present 

 title. 



Paramonas globosa, From. sp. Pl. XX. Fig. i. 



Body spherical, transparent, enclosing red granules ; contractile vesicle 

 subcentral ; oral aperture conspicuous, situated at the base of the flagellum. 

 Length 1-2400". Hab. — Fresh water. 



Identical with the Monas globosa of De Fromentel. 



Paramonas ovum, From. sp. 



Body ovate, transparent, coarsely granulate ; flagellum constantly 

 vibrating ; mouth situated close to the base of this organ. Length 1-1500". 

 Hab. — Fresh water. 



The Monas ovum of De Fromentel. 



Paramonas stellata, From. sp. Pl. XX. Fig. 2. 



Body ovate or spherical ; endoplasm green and granulate; oral aperture 

 apical, stellate ; flagellum long and fine, constantly vibrating. Length 

 1-1500". Hab. — Freshwater. 



Both this and the succeeding species, characterized by De Fromontel as having 

 their endoplasmic substance coloured green, are referred provisionally only to the 

 genus Paramonas. If such coloured matter represents a permanent constituent. 



* ' Etudes sur les Microzoaires,' Paris, 1876. 



