"an 
— 16 — 
with a deep constriction in the middle. Length of frond 
.0058°—0063”. Width .0036—-004. 
C.pectinoides, n.sp. — Frond suborbicular, some- 
what longer than broad, constriction linear. Segments semi- 
orbicular, undulate on the margins with twenty or more cre- 
nulations, roughened with geminate rows of pearly granules 
symetrically arranged in radiating lines. On green fronds 
the united twinned granules appear oblong and the crenu- 
lations somewhat dentate. Each segment furnished at base 
with a rounded protuberance most distinctly evidenced by 
side view. The resemblance to forms of many seaside shells 
suggested the name. Frond .0025° long, and .0018° broad. 
14) Euastrum, Ehrb. — E. verrucosum, Ehrb. — 
E.pectinatum, Breb. — E. oblongum, Ralfs. — 
E. ampullaceum, Ralfs. — E. didelta, Ralfs. — 
E. elegans, Ktz. — E. binale, Ralfs. — E. ornatum, 
Wood. — E. circulare, Hassel. — E. rostratum, 
Ralts. 
15) Micrasterias, Ag. —M. oscitans, var. pinnati- 
fida, Ktz. var. inflata, new. — M. Americana 
var. recta, new. — M. Crux-Melitensis, Ralfs. — 
M. truncata, Breb. — M. furcata, Ag. — M. Jen- 
neri, Ralfs. — M. foliacea, Bailey. — M. multi- 
fida, n. sp. — M. denticulata, Breb. — M. dispu- 
tata, Wood. — M. muricata, Raltfs. 
Three forms are considered new. M. oscitans, var. in- 
flata differs from the typical forms in having the lateral 
lobes not ““narrow and conical‘“ but broad, with sides nearly 
parallel and often inflated or widened at the ends. M. 
Americana, var. recta differs from the normal form in ha- 
ving the terminal lobe, not “concave and bipartite at the 
angles,‘“ but straight and entire, with t wo conical tubercles 
on the margin towards the lateral ends. 
M. multifida, n. sp. Frond punctate, five lobed: 
basal lobe bifid, and middle lobe trifid, and each section 
again bifid, and by a shorter sinus bifurcate at apices; or, 
segments may be called eleven lobed; the lateral lobes dee- 
ply bisected, sinus more or less rounded at base, sections 
forked. Terminal lobe narrow, not exerted, sinus wide, 
angles bifurcate. Rarely with nine lobes. .005” wide. 
005-006 long. 
16) Staurastrum, Meyen — St. muticum, Breb. — 
St. orbiculare, Ralfs. — St.brevispina, Breb. — 
St. Dickiei, Ralfs. — St. dejectum, Breb. — St. 
Avicula, Breb.— St.brachiatum, Ralfs. 
St.bifidum, Breb. — St. Margaritaceum, Menegh. 
