1894.] On Some Species of Micrasterias. 59. 
156u. In another respect the latter are remarkable. The 
typical form, as is well known, has each of the four lateral 
lobes deeply bifid, but such specimens are not numerous in 
this material. The cell shows a decided tendency toward a 
form with simple lobes (fig. 14). Scores of specimens were 
examined of which no record was made, but of thirty taken 
at random which were measured, eleven were typical, two had 
one simple lobe, five had two, two had three and the same 
number four, three had but two typical lobes each, three had 
but one, while two were of the form shown in fig. 14, with all 
the lobes simple. Some of these varieties are shown in figs. 
9-13. Sometimes all the abnormal lobes are in one semicell, 
while the other is normal, but quite as often some lobes of 
each are simple, and these may be on the same or opposite 
sides of the frond. A curious and rather puzzling fact is that 
the lobes nearest the base of the semicell show the greatest 
tendency to this variation. If there are not more than four 
simple lobes these are almost invariably the basal ones. Only 
one exception to this was found among all the specimens ex- 
amined. | 
Another noteworthy fact is that the abnormal forms are al- 
Most invariably larger than the typical. Of the thirty speci- 
mens measured the eleven fypical ones averaged 133s, while 
the others averaged 163, and the average of those hav- 
ing over four simple lobes was 182, with extremes of 165 and 
200. Only two abnormal specimens measured less than 
140M, Often the difference could be seen in a single cell, 
the varying half being decidedly larger than the other. 
ae oF material collected in Connecticut, only a week or 
ii alter the former collection, these variations were very in- 
are but they were found occasionally. Of thirty speci- 
mri ay but three were of the typical form. Of the three, 
es a one semicell of the typical form, while the other 
Tur a form, with all the lobes simple. 
Wego — described and figured a variety decurta’* of M. 
cs ay i. which seems to be this simple form. He says 
Only tivo It is ‘‘a strange’ and apparently abnormal form. 
doubt semicells seen, of which one possessed a curious 
€ lobelet.” His material was from Watertown, N. Y. 
It j : 
is hardly necessary to call attention to the close re- 
14 
On 
1885, Some new and rare desmids. Jour. Royal Micr. Soc. 5; 936. p/. 16. f. r0. 
