244 NEMATOGENZ. 
Sizz. Cells :003--004 mm., heterocysts rather longer. 
Spores 014 x :025-03 mm. 
Kirch. Alg. Schl. 237. Rabh. Alg. Eur. ii., 186. 
Anabaina impalpebralis, Hass. Alg. 283, t. 75, f. 3. 
In ditches and ponds. 
Plate XCV. fig. 1. Trichomes with heterocysts and spores X 400. 
Cylindrospermum catenatum. Ral/s Ann. Nat. Hist. t. 8, f. 14. 
Stratum bluish green. Trichomes very fine elongated 
straight, or slightly flexuous, generally parallel, moniliform. 
Joints spherical minute. Heterocysts oval. Spores 2-8 in 
each series, at first spherical, then more or less oval, but little 
broader than the heterocysts. 
Size. Cells about -003 mm., heterocysts a little longer, 
spores about ‘006 x :008 mm. 
Rabh. Alg. Exs. No. 1358. 
In fresh water. 
Clearly distinguished from the preceding species by its nu- 
merous spores. 
Plate XCV. fig. 2. Trichomes with heterocysts and spores X 400. 
GENUS 99. NODULARIA. Mertens. (1822.) 
Trichomes distinctly vaginate, with very closely compressed 
disc-shaped joints, collected in a gelatinous or membranaceous 
irregularly diffused stratum. Heterocysts intercalated at re- 
gular intervals, vegetative joints nearly equal, transversely 
compressed. Spores fuscous, or golden yellow, becoming tawny, 
globose, slightly compressed. 
Nodularia litorea. (Thw.) Thur. Ann. Sci. Nat. 1875, 378. 
Scarcely gelatinous, forming a deep green fleecy covering to 
floating plants on which it occurs. Trichomes of considerable 
diameter, nearly straight. Joints of a beautiful blue green 
colour, very short and compressed, giving the filaments the ap- 
pearance of an Oscillaria. Heterocysts pale reddish. Spores 
elliptical, at length acquiring a deep brown colour, 
Size. Trichome, without sheath, -012 mm. 
Born. and Thur. Notes Algol. ii., 121, t. 29, f. 1-9. 
Spermosira litorea, Kutz. Phy. Gen. 218. Rabh. Alg. Eur. 
ii, 186. Harv. Phy. Britt. t. 113, f. ¢. 
In muddy, brackish ditches. 
