Desmidie^l iNFrsoRiAt ANiMAtrrtE?. 245 



Mtckastehtas fimhriata. — Orbicular, smooth ; lobes dichotomously 

 incised, ultimate sub-divisions obtusely emarginate, spinoso-miicro- 

 nate. Length 1 -108th. Breadth 1-1 19th. 



M. radwsa= Mmstrmn Sol. (Ehr.) — Orbicular, smooth; lobes 

 dichotomously divided; ultimate sub- divisions inflated, attenuated 

 at the end, bidentate or mucronate. Differs fi'om M. rotata in its 

 inflated sub-divisions. Length 1-1 38th. Breadth 1 -138th. 



M. papillifera. — Orbicular, with marginal gland-like teeth ; 

 segments five-lobed ; lobes dichotomously incised ; the principal 

 sinuses bordered by a row of minute granules. Sporangia similar 

 to those of M. denticidata, but smaller. Endochrome brownish green. 

 Length l-221th. to l-20,5th. Breadth l-238th. to l-211th. 



* * Frond suhcllipfie ; segments three or five-loled ; lobes radiant, 

 the end one someuhat exserted and divergent. 



M.fureata. — Segments five-lobed ; lobes bifid; their divisions linear, 

 divergent, and forked at the apex. Frond smaller than that of M. 

 rota fa ; its outline broadly elliptic, sometimes almost circular. En* 

 dochrome green. Length 1-1 35th. Breadth 1-1 56th. Very rare. 



M. crux-melitensis = Euastrum crux-meliiends. (Ehr.) — Frond 

 rotundato elliptic ; segments sub-five-lobed ; lobes bifid, sub-divisions 

 short, stout and bidentate at the apex. Size same as M. fureata, 

 and similarly di\'ided. Empty fronds very delicately punctated. 

 Length 1 -200th. Breadth l-221th. Very rare. (P. 2. f. 124.) 



M. americana. = Euastrum. Americanum. (Ehr.) — Angular ellip- 

 tic; segments thrce-lobed, end lobe with bipartite angles; lateral 

 lobes broad, margin concave, inciso-serrate. (P. 13. f. 44.) 



Var. («.) — Serratui'es distinct. 



Var. {b.) — Scrratures obscui-e. Length 1 -204th. Breadth 1 -254th. 

 Rare. 



*** Fronds orbicular ; segments obscurely five-lobed ; the end one 

 broadest. 



M. truncata. = Exiastrum Rota. (Ehr.) — Orbicular, segments 

 with five-shallow lobes, the end one very broad, truncated ; lateral 

 ones inciso-dentate. Length 1 -240th. Breadth 1 -250th. 



M. erenata diftcrs from M. truncata in the convex margin of its 

 end lobes, and the absence of teeth on the lateral ones. Length 

 l-244th. Breadth l-263rd. 



