1892.] MICROSCOPICAL JOURNAL. 237 



Spirolina (Fig. lo) another form similar in a general way to 

 Rotalia is found. Lieberktihnias Gromia^ Rotalia^ atid Spiro- 

 li?ia are all marine forms ; they are only a few members of the 

 very large order Foratniiiifera. 



Peridinium uberrimum has an oval body encircled by a 

 shallow groove. At one end the body is pitted in and here is 

 placed a vibratile lash or flagellum. The body is entirely destitute 

 of a covering, except as the somewhat firmer outei- portions of 

 the protoplasm may constitute such, and the protoplasm is not 

 vacuolated. 



But the outline of the body is definite and the flagellum is very 

 active and persists. In addition to the strong flagellum the body 

 on its general surface bears minute active processes, believed to be 

 of the ectosarc, which are called cilia, and which, together with 

 the flagellum, are motor agents. Peridmium is thus like and un- 

 like Amceba. Like Atnccba^ it is a naked mass of protoplasm with 

 a single nucleus ; like it, has motile prolongations of the proto- 

 plasm ; but, unlike it, the body outline is permanent and pseudo- 

 podia are definite in position and mode of action and very active. 

 It is possible mentally to derive Peridinium from an amoeba-form 

 source by imagining only a few changes, namely, a single perma- 

 nent pseudopod as in A. radiosa^ general distribution of minute 

 active cilia somewhat as in A. villosa^ and tiie permanent oval 

 shape and equatorial depression. And this illustrates what is 

 meant when we say that these animals are arrangeable in series 

 in which we step from term to term with breaks, perhaps, but no 

 very great ones. 



Noctiluca miliaris (fig. 17) is an organism much larger 

 than the Protozoa in general, being as large as a grain of clover 

 seed. It lives in the ocean and owes its name to the peculiar 

 power of prodticing light or phosphorescence which it possesses 

 in common with a great may marine animals. In N^octiluca the 

 body has the shape of a helmet. It is transparent, of fixed outline, 

 and the outer surface, while not forming any definite and dis- 

 tinct shell, is firm and cuticular. The cuticle by an infolding 

 forms a sort of cup, from within which a long and strong flagel- 

 lum proceeds. The protoplasm does not entirely fill the body 

 but is in the form of a central mass and branched threads stretch- 

 ing across vacuolated spaces to a thin layer lining the cuticle. 

 Within the first cup there is a second, smaller cup, and within 

 this a smaller flagellum ; this is used in taking in food, the large 

 lash being the organ of locomotion. There are no cilia. Nocti- 

 luca increases by division and figiu'e 17- shows one stage near 

 the end of the process. 



Codosiga umbellata (figs. iS, 19, 30), a fresh-water animal, 

 is unlike any of the animals thus far considered in the fact that it 

 is a colony of similar members mechanically connected by slender 

 stems but having no vital relation. Each member of the colony 

 (see fig. 19) consists of a protoplasmic body with two contractile 



