1897 | SOME NEW SPECIES OF MINNESOTA ALGA IOI 
moniliform in lower portions, tapering to a point; articulations 
in lower portion of filament equal in length to diameter, shorter 
in upper portions; heterocyst basal, globose or depressed glo- 
bose, diameter equal to or a little smaller than that of filament. 
This plant does not seem to be very near any of the species of Dichothrix 
as described by Bornet and Flahault. The filaments are strongly agglutinated, 
and this with the moniliform character of the trichomes make it peculiar. 
LYNGBYA MARTENSIANA Calcarea Tilden, Am. Alg. Cent. II. no. 
178. 1896. (pl. LX., fig. g)—In extended strata throughout upper 
portions of calcareous deposit. Filaments elongate, straight, 
flexible, somewhat unequal in size, average 6.5-7.5~ in diam- 
eter; sheath very distinct, hyaline, smooth or rough; trichomes 
dull zruginous, violet, or rarely brown, frequently interrupted, 
not constricted at joints, not or very rarely attenuate at apex, 
5—-6.5#in diameter ; articulations 2-3 times shorter than diameter, 
average 2.54 long; dissepiments often inconspicuous or marked 
with granules; apical cell rotund; calyptra none. 
ZL. martensiana has been found only in thermal waters. The temperature 
of the water in the tank is 12° C. during the summer. The filaments of the 
species are somewhat larger and the articulations shorter than those of the 
variety, but otherwise the points agree very well. 
Lyngbya nana Tilden, Am. Alg. Cent. II. no. 179. 1896. (pv. 
tX., fig. 5)—In extended strata on or near surface of deposit. 
Filaments 1I.g# in diameter, straight; sheath delicate, hyaline, 
smooth ; trichomes very pale steel color becoming violet later 
in the season, not constricted at the joints; articulations 1.6» in 
diameter, quadrate or 1.5 times the diameter in length; apical 
cell rotund. : 
In Gomont’s monograph there are but four species of Lyngbya described 
whose size will permit of comparison with L. mana. Of these L. Lagerheimit 
is easily distinguished from it by the spiral filaments ; ZL. »7vu/ariarum by the 
constriction at the dissepiments, length of the articulations and habit of 
growth; ZL. ochracea differs in the peculiar character of its stratum; Z. pur- 
urea agrees more nearly than the others. The measurements are alike, the 
joints show no constriction. The violet color, however, which in the last 
_ Species appears to be cieeeate: is Auman to a certain stage only < £. nana. 
a itat, lik ‘ ly separate the two. 
