296 
shows a marked papilla on each side. It seems to be truly a 
Xanthidium. 
X, Tylerianum West. (X. antilopaeum Kitz. var. truncatum 
Hast. Wollein Desmids of the U.S. 1892 edition.) Ithaca, N.Y. 
Commonand typical. Although first described by Hastings, West's 
name must take precedence, since Hastings published the species 
merely in a local newspaper. 
The following species are believed to be new : 
ARTHRODESMUS MICHIGANENSIS n. sp. Fig. 12. 
Size medium. Length about one-third greater than breadth. 
Sinus gaping, broadly rounded, semi-cells being connected by a 
short neck. Semi-cells sub-elliptical, with the apex of the cell 
drawn out into a broad truncated lobe, and each end armed with 
a long slightly recurved spine. In vertical view rhombic elliptical 
with a long spine at each end. Side view circular. Diam.=24- 
30 #; length= 36-40 ; thick=16-18 yp; isth—=7-9 p. Whitmore 
Lake, Mich. Frequent. Type in herb. Johnson, 427. 
COSMOCLADIUM TUMIDUM n. sp. Fig. 23. 
Minute. Length and breadth nearly equal. Cells usually 
joined in fours by a hyaline, mostly unbranched filament. Great- 
est diameter of cell placed at right angles to the connecting fila- 
ments. Sinus deep, linear; semi-cells hexagonal elliptic, with 
apex flattened. In vertical view elliptical with slight but distinct 
median inflation. $ide view nearly circular. Diam=8 yz; length 
=9p; thick=5; isth—=2y. Whitmore Lake, Mich. Type in 
herb. Johnson, 455. 
This resembles C. subramosum Schmidle, but differs from it in 
its shorter cell, and in the median inflation of the semi-cell. j 
_ Ido not feel perfectly sure that Cosmocladium should be sepa- 
rated from Cosmarium. 
Cosmarium Paciricum n. sp. Fig. 25. 
_ Small. Length about one-fourth greater than the breadth. 
Sinus strongly gaping. Isthmus narrow. Semi-cells sub-ellipti- 
cal. Sides curving regularly from the base to above the middle, 
then converging by a sharp angle to form the rounded end. End 
view elliptical, with no inflation. Side view nearly circular. A 
single pyrenoid in each semi-cell. Membrane punctate. Diam. 
=25-28 ; length= 32-34 4; thick=15-17; isth=6y. Sisson, 
Siskiyou county, California. Altitude 3000 feet. M. A. Howe 
coll. Type in herb. Johnson, 402. 
