262 
W. E. WADE 
duobus ordinihiis arcuatis regiilariter irregularilerve dispositis. 
Semicellnla a vertice visa elliptica, polo utroqne quattiinr spinns 
in planis differentibiis ordinaias ferente. Celliila u long., cuin 
spinis 70 a long., 55 y. lut., ciim spinis 72 a lat. Isihmiis 22 y. lat. 
Sejiiicells subsemicirciilar witli two pairs of spines borne on 
latéral margins. the hnver ])air slightly curvecl and inscrted a 
slight distance apart and in a different vertical plane on the 
latéral margins, the upper pair inserted close together at the 
apical angles; the upper central région of the semicell wall 
thickened and scrobiculate, the scrobiculations arrangcd regu- 
larly or irregularly in two arcuate rows. Vertical view elliptic 
with cach pôle bcaring four spines arranged in different planes. 
Cell length 64 u., cell length with spines 70 u, cell width 55 |i, cell 
width with spines 72 u., isthmus 22 jx. Old intermittent lake west 
of St. Ignace on route 2, Mackinac County, Michigan. 
This form ditfers froin var. john.^onii (West and West) G. 
M. Smith in possessing four spines irregularly disposed upon the 
latéral margin whereas the variety has two spines that are 
arranged in the saine plane on the latéral margin. The scrobicu¬ 
lations are arranged about half-way between the apex and the 
face of the semicells, and thus lower than in the variety. In 
addition, the scrobiculations are arranged in a double irregular 
row in a subarcuate band, in contrast to the single irregular 
row found just below the apex in the variety. The organism 
figured by T.^ylor (1934) as A’, antilopaenm var. hebridarinm 
West and West is closely relatcd to this form because of shape 
of semicells and the number and arrangement of spines, 
although the arrangement of scrobiculations on the face of the 
semicell is dilîerent. The author believes Sm[th's (1924a) A’. 
subhasliferum var. johnsonii fa. and the Michigan specimens 
are distinctive and should thus be designated with a form naine. 
Micrasterias Agardh. 
MicrasierUis nordstedtiana Wolle. Barry County. 
M. papillifera var. speciosa (Wolie) Krieger. Chippewa County. 
M. radiata var. psemlocnix Gronbl. New record for North America, 
Schoolcraft County. 
M. truncafa var. qiiadrata Bulnh. fa. Specimens from Roscommon 
County are intermcdiate between this variety and variety 
tridentata Benn. 
M. truncata var. semi-radiata (Naeg.) Cleve. Presque Isle. 
Staurastrum Meyen. 
Staurastriim affine West and West fa. A single specimen from 
