THE I'l.oi; \ (il M.r.i; \>K \. |;; 



13. 9EICRASTERIAS Ao. Mora H, 642. 1827. 



Cells simple, lenticular, deeply constricted in the center, fronl \ Lew orbioolar 

 or broadly elliptical; half-cells:; 5 Lobed; lateral Lobes entire or inoisel; 

 lobulate, end lobe entire, sinuate or emarginate, Bometimea with angles 

 produced and bifid; zygospore globose, armed with long, Btraighl 

 which are often bifid or trilid at the ends. 

 Etymology; Greek ptKpog, small, and aanjpiag, star. 



Micrasterias gpeciosa Wolle Bull. Torr. Bot. Club XII. 1885. 



Small, longer than broad; sinus broad, half-cells 4-lobed; lateral lobes on 

 equal, the basal pair with fewer divisions than the intermediate, term 

 inal lobe rather narrow, linear; end exserted and dilated, with 3 mnori 

 at each angle. 



Minden. PI. VII., Fig. 22. 



Micrasterias americana (Ehrenb.) Kuetz. Spec. Alg. 171. 1849. 



Euastrum americamim Ehrenb. Verb. u. Einfl. Mikr. lob. in S. u. X. Am. 125. 

 1843. 

 Half cells 3-lobed; lateral lobes bilobulate, margins concave, incised, Bert ite, 

 end lobe broad, cuneate, exserted, produced into 1 rigid, truncate pro 

 cesses, subdivisions of lateral lobes dentate at the extremities; diameter 

 100-115 /j., length one-third greater. 

 Minden. PI. VI., Fig. 1. 



14. STAITRASTRUM Meten Nov. Act. Leopol. XIV 227. 1820. 



More or less deeply constricted in the middle; half-colls in end view.'! many 



angled or lobed; angles obtusely rounded, acute, or produced into awns; 



cell membrane smooth, punctate, or aculeate; zygospore orbicular, spin. 



ose; spines at first hair-like, afterwards stout. 

 Etymology: Greek aravpoq, cross, and aorpov, star. 



Stanrast ru in aristifernm Ralfs Brit. Desm. 123. 1848. 



Smooth; half-cells triangular, the lobes in front view prolonged into main 

 millate, awned projections which are somewhat constricted at the Las.., 

 end view with 3 or 4 awned lobes, sides deeply concave at the oenter; 

 diameter 13-20 p. without awns. 



Minden. PI. VII., Fig. 21, a, b. 



Staurastrnm polymorph u m Breb. in Ralfs Brit. Desm. 135. 1848. 



Half-cells in front view broadly elliptical, with the sides tapering Into short. 

 stout processes, ends tipped with 3 or l small spines; membrane rough 

 with minute, sometimes acute, granules; end riew triangular, angles trun- 

 cate or drawn out into short, stout processes, ends tipped with small 

 spines; diameter 25-30 u; zygospores orbicular, armed with eloi 

 spines forked at the tip. 

 Thedford. PI. VII, Fig. 19, a, b. 



Stanrastrnm gracile Ralfs in Ann. & Mag. X. II. XV .. 155. 



Granular, roughened; granules arranged In transverse series; half -oells too 

 trally inflated, dorsally truncate, produced Into 3 radiate processes, 



of which has 3 slender spines; diameter 40 p. 

 Thedford. PI. VII., Fig. 17, a, b. 



