NOSTOCEE 233 
Hormosiphon macrosporus, Kutz. Tab. Phye. ii., t. 18, f. 1. 
Diplocolon Heppii, Itzig. Phyc. Stud. t. 11, f. 8-12. 
Nostoe pyreniacum, Ripart. Bull. Soc. Bot. Fr. (1868.) 
Nostoc ichthyon, Rabh. Alg. Eur. ii., 164. 
On rocks among moss. 
Plate XC. figs. 1, 2. Involved trichomes of V. macrosporum x 400 ; 
fig. 3, development of hormogone, x 400, after Borzi. 
Nostoc ceruleum. Lyngb. Hydr. Dan. t. 68, f. 3B. 
Fronds, small, globose or subglobose (1 to 4 lines), fixed or 
free swimming, usually gregarious, blue or greenish-blue. 
Trichomes dissimilar, unequal, joints of two forms, the one 
(young) elongated, the other larger, nearly spherical, some- 
times filled with opaque granules. 
Sizz. Joints ‘004-007 mm., heterocysts ‘008 mm. 
Born. & Thuret Notes Alg.p.114. Rabh. Alg. Eur. ii., 167. 
Nord. & Wittr. Alg. ixs. No. 98. Grev. Sc. Crypt. Fl. t.131. 
Hass. Alg. 293, t. 76, f. 11, t. 75, f. 10, t. 74, f. 1. Eng. Fl. 
v., 400. Harv. Man. 1838. Gray Arr. i, 352. 
Nostoc cerulescens, Rabh. Alg. Eur. ii., 168. 
Nostoc Jizigsohnit, Rabh. Alg. Eur, ii., 168. 
On mosses and submerged plants. 
Plate XCU. fig. 4. Plants of Wostoe carulewm natural size ; fig. 5. 
trichomes x 400; fig. 6, portion of trichome x 600. 
Nostoc pruniforme. dg. Disp. Alg. p. 45. 
Frond from the size of a peato that of a damson, or larger, 
olive or dark sruginous-green, when old becoming blackish- 
brown, with a curiaceous periderm, and watery within. 
Trichomes loosely interwoven, joints subglobose, compressed, 
closely connected. Heterocysts globose, usually terminal. 
Sizz. Joints ‘004-005 mm., heterocysts ‘006-007 mm. 
Born, & Thuret Notes Alg. p. 116. Rabh. Ale. Eur. ii. 
Kutz. Tab, Phy. ii., t. 4, f. 4. Witt. © Nord. Alg. Exs, 97, 
276.(?) Berk. Glean. t.19,f.2. Hass, Alg. 291, t. 76, f. 
3,4. Eng. Fl. v., 399. Harv. Man. 1838. Gray Arr. i, 852. 
Ulva pruniformis, Huds. Ang. ii., 572. Abbot. Bedf. 274. 
With. Arr. iv., 120. Hull. Br. Fl. 310. 
Nostoc coccymelon, Kutz. Tab. Phye. ii, t. 4, f. 8. 
In freshwater pools, rivulets, &c. 
Plate XCII. fig. 7. Nostoc pruniforme, natural size ; fig. 8, trichome 
«x 400; fig. 9, portion of trichome, with spores in course of formation 
x 600, 
