THE BREAKING OF THE SHROPSHIRE MERES. 
127 
Nodularia Harveyana, Thur. 
Trichomes much curved, composed of cells nearly as long as broad. 
Ileterocysts subquadrate, rather longer than wide, and of the same 
width as the joints. Spores spherical, almost twice the diameter 
of the joints. 
Size.—Trichomes, *0065 mm. diam. 
Born, and Thur. Notes Alg. ii., t. 29, f. 14-16. 
Spermosira Harveyana, Thw. in Harv. Phyc. Britt., t. 173, f.c. Rabh. Alg. 
Eur. ii., 295. 
The Shropshire specimens have a decided sheath, enclosing the 
trichomes which terminate at the heterocyst, unless the heterocyst 
is terminal when it surrounds it. 
Plate V., fig. 4. (a) Deposit of the alga from a drop of water, natural size. 
( b ) The trichomes magnified 70 times, (c) A trichome showing its 
sheath terminating near the centre of the intercalated heterocysts. 
Cells of the trichome, 10x10^; heterocysts, 10—15^. 
I first referred my specimens to Dolichospermum Ralfsii (Kutz .) = Anabcena 
Ralfsii (Kutz.), but the size and form of the cells, and the presence of 
a sheath, lead me to conclude I was in error. At the same time 
I should remark that the trichomes in my specimens were in no 
instance “ much curved.” 
Oseillaria serugeseens, Drum. 
Stratum of a fine deep green, highly gelatinous ; when dried, asruginous, 
blue, and glossy; trichomes very slender, opaque green, conglomerated 
in large masses, rarely floating, or broken into fragments and 
suspended like cloudy flocculi in the water, joints about half their 
diameter long. 
Size.—Trichomes '005 mm. diam. 
Oscillatoria cerugescens, Hass. Alg. 249, t. 72, f. 2. Harv. Man. 163. 
Plate 2, fig. 5. ( a ) A group of trichomes magnified 70 times, (b) Other 
trichomes magnified about 350 times. 
Gloeotriehia eehinata (English Botany). 
Globose, very minute, dark coloured, compact. Threads fastigiate, 
attenuated upwards to the apex, closely cohering, articulated ; spores 
cylindrical; heterocysts basal, globose ; sheaths very narrow, or 
almost inconspicuous. 
Trichomes ’007 mm. at base, *25 mm. long. 
Ghcetophora punctiformis , Kutz. Tab. Phyc. iii., p. 4, t. 18, f. 2. Rabh. 
Alg. Eur. iii,, 386. 
Echinella articulata , Eng. Flo. v., p. 398. Eng. Bot. ii., t. 2555. Harv. 
Man. 187. 
Conferva eehinata , Eng. Bot. i., t. 1378. 
Conferva echinulata , Gray. Arr. i., 310. 
In lakes, ponds, &c. 
Plate IV., fig. 1. (a) Group of specimens, natural size, (b) Section of 
an individual showing the hollow centre and the radiating trichomes, 
magnified 70 times, (c and d) Trichomes with their basal spherical 
heterocysts. ( e and /) Two hormogonia in different stages of develop¬ 
ment, (/) earlier, (e) later, (g) A group of five basal heterocysts 
detached, c to g magnified 350 times. 
June, 1893. 
