226 American Quarterly Microscopical Journal. » 



Sc. polyviorphus, Wood. Cells fusiform, or oval, or elliptic, or glo- 

 bose, single or 2-7 conjoined, furnished in most cases with a single 

 spine, sometimes 2, at each end ; spines exceedingly slender and acute, 

 straight, moderately long, inclined. 



Sc. rotundatus. Wood. Cells globose or sub-globose, armed with 3-5 

 very long, slender, acute, straight spines, single or in pairs, or 3-4 

 closely conjoined in a two-fold rank (Wood).] 



\b. Cells unarmed.] 

 Sc. acuius, M. Cells spindle-shaped, the outer ones crescent- 

 shaped. [2-4 times longer than broad.] 

 Sc. obtusus., M. Cells elliptic, obtuse. 



7. Gen. Fediastrujn, Meyen. Cells smooth, lobed, connected 

 into disk-like rosettes, often perforated. Swarm-spores 

 produced by repeated division of the contents, make their 

 exit and arrange themselves into new rosettes. [Cells 

 polygonal.] 

 P. Boryanum, IVIengh. Cells of disk polygonal, connected with- 

 out any gaps. Outer cells with two lobes, horned. 

 F. pertusum, Ktz. Cells four-cornered with carved borders ; 

 disk therefore perforate. Outer cells deeply bi-lobed, 

 lobes horned. In turf-bogs. 

 P.E/irenbcrgii, A. Br. Cells connected without gaps. Outer 

 cells club-shaped, but deeply indented, lobes two-pointed. 

 P.rotula, A. Br. Cells all bi-lobed, family perforate. Outer 

 cells growing together only at the base, deeply cleft, lobes 

 two-toothed. 

 [P. Selencea, Ktz. Cells crescent shaped, arranged in one or more 

 circles round one or two central ones, connecting medium colored 

 (Wood). 



P. cotistricttmi, Hass. Cells varying in number and arrangement ; 

 outer cells suddenly contracted into two short, cylindrical, obtuse pro- 

 cesses (Wood). 



P. simplex, Meyen. Peripheral cells, ovate-cuspid, 8- 10- 16 joined at 

 bases. 



8. Gen. Protococcus, Ag. Spheroidal cells, swimming free, or out of 

 water in thin pulverulent stratum. Protoplasm first green, homoge- 

 neous, later granular, green, or reddish. 



P. nov. sp. ? Green cells, globose or angular, accumulated in a pul- 

 verulent stratum, often closely united int.o families, cytioderm mostly 

 not distinct ; resting-spores round with 2 or 3 thick coats ; zoospores 

 oval or roundish, or somewhat elliptical, with two cilia (Wood). 



Chlorococcum, Fries, is a genus given by Wood, as follows : " Cells 

 spheroidal, single, free, furnished with a chlorophyllous vescicle and a 



