MICRASTERIAS. Ill 



Section II.- Cells subelliptic ; semicells three or five lobed ; lobes radiate, the 

 end lobe somewhal exserted, divided and arms divergent. 



M. furcata, (Ag.) Ralfs. Plate XXXV, figs. 5, 6. 



< Jells five lobed ; lobes 1 i H 1 . their divisions linear, divergent, 

 and forked at the apex. The end lobe exserted, its divisions 

 divergent, producing a wide -hallow -inns. 



Diameter 150-180//.; common. 



M. psbudofurcata, Wolle. Plate XXX\'. fig. I. 



Five lobed, simple, not bifid ; sometimes the lateral lobes 

 appear more like one bifid lobe on each side : in either case 

 only half as many lateral arm- as characterize the preceding 

 species, M.furccUa. 



Diameter 150-160 ". 



Nol as frequenl as the true form, but it has a habitat in 

 many localities in the Middle Stab 3. 



Var. MINnK, Wolle. Plate XXXVII, fig. II. 



Small, not one-half the diameter of the typical form, but 

 so Dearly like it in outline, I note it as a variety. Had but 

 two or three specimens, from Minneapolis, Minn. 



M. Cbux-Melitensis, Ehrb. Plate WW. fig. 3. 



Semicells indistinctly five lobed ; loin- bifid, subdivisions 

 short, and furcate at the apices. 



Diameter 100-125 ". 



Not 80 frequent as M. furcata,to which it often hears a 

 close resemblance ; it is similarly divided, hut the incisions 

 are oot so deep, the subdivisions nol bo elongated, rather 

 stouter and less divergent : end lobe less exserted. 



M. dichotoma, Wolle. Plate LII, fig. 2. 



Somewhat longer than broad, smooth or finely punctate; 

 semicells three lobed ; lateral lobes twice bifid; the ultimate 

 lobules (four resulting from one) deeply furcate or clawed at 

 the ends; the polar or end lobe exserted on a cylindrical neck 

 with two diverging arms clawed at the ends. 



Diameter with arms 175-200 u. ; length the same to one- 

 fourth greater. Length of body 1 1 5 ,. ; breadth of neck 

 15-17 //.. 



