’ 289 - 
base of the semi-cells is shorter, and on the end there is a double 
row of large divided granules along each side. The differences do 
hot seem great enough to justify separation as a species or even 
as a variety. 
St. leptocladum Nordst. var. cornutum Wille (Conn.) Fig. 3. 
The semi-cells show a row of short downward-pointing spines 
around the base; otherwise the specimens are like the original 
figures, 
St. Ophiura Lund. (N. Y.and Conn.). Frequent. Most of the 
specimens have but five or six rays, though a few show seven or 
eight. 
St. quadrispinatum Turn. (Edgemoor, Ind.). 
St. Ravenelii Wood (Northfield, Mich.). The specimens do 
Not show such an irregularity of the spines as mentioned by Wolle. 
AXanthidium cristatum Breb, and X. fasciculatum Ehrenb. have 
been frequently found, but by far the most common form is that 
shown in Fig. ti: it ap probably a form of X, antilopeum (Breb.) 
Kutz, var. Minneapoliense Wolle, but the spine on the side of the 
cell arises invariably de/ow the row of granules. Moreover, there 
is a fifth spine on each end of the cell, nearly between the lower 
Pair. In rare cases this is short or lacking. Prof. Nordstedt has 
figured] a cell of LX. antilopeum (Breb.) Kutz, var. polymazum 
Nordst, one semi-cell of which shows this extra spine as a short 
Stub. As the species seems so variable, it is hardly advisable to 
give a special name to this form, which doubtless runs into the 
others, 
Besides the above named Desmids several new species have 
been found, and descriptions of them are here given. 
_ Cosmarium nudiceps n. sp., Fig. 12. Length of cell 1% times 
Its breadth. Sinus deep, nearly linear. Semi-cells almost semi- 
circular, with two granules, one above the other at the base, and 
Often traces of one or more above. On the side of the semi-cell 
and within the margin, nine diverging rows of large granules, the 
middle, with the first and third on each side, of three; the second 
of four and the outer of two. In vertical view elliptic with a band 
through the center bare, and the granules on each side. Length, 
48-50 pn; diameter, 36-40 #; thickness, 25 #; isthmus, 12-14 P. 
Type in Herb. Johnson, 214. New Baltimore, Mich. 
Se tla 
Li 
‘i Bidrag till Kannedomen om sydligare Norges Desmidiéer, p/. 7, fig. 20 (1873). 
