PALMELLACEZ. 25 
globose, afterwards elongated, or elliptic, sometimes conoid, one 
or other pole colourless, arranged more or less regularly in longi- 
tudinal families; tegument thick, at length diffluent, cells 
dividing in one direction, chiefly at the apex or periphery of the 
thallus, Propagation by means of agile gonidia. 
Hydrurus penicellatus. Ag. Syst. p. 24. 
Thallus rather cartilaginous, olivaceous, of variable thickness, 
simple and naked below, divided above, and villous with dense 
fibrils. Internal cells elliptical or somewhat lanceolate ; tegu- 
ment very thin, scarce visible ; contents homogenous. 
Rabh. Alg. iii. 50. 
Hydrurus fetidus, Vauch. Kirch. Alg. Schl. p. 106. ° 
var. e. Ducluzelii. Rabh. Alg, 111.50. 
Thallus from an inch to a foot long, oftentimes sparingly 
branched, plumose with very dense fibrils. 
Size. Cells :006-'0095 mm. (Rabh.). 
Hydrurus Ducluzelit, Ag. Consp. p. 27, Hass. Alg. t. 77, f. 
3. Rabh. Exs. 176, 873, 1193. 
Batrachospermum myosurus, Ducluz. Conf. Montp. p. 76. 
Palmella myosurus, Lyngb, Hydr., t. 68, E. 
Cluzella myosurus, Bory. Dict. iv. 234, 
In alpine rivulets, on stones, rocks, &. 
“Root scutate, blackish, hard. Fronds clustered, solid, very gela- 
tinous, 2-6 inches long or more, 2-4 lines in diameter, freely waving in 
the water, attenuated towards the apex, branched; branches scattered, 
alternate, elongate. slender, beset with other more slender, short ramuii. 
Gelatinous mass pellucid, viscid, colourless under the microscope, without 
apparent margin, unless as the granules imbedded within its substance 
indicate such; these are globose, green, formed on the stem and primary 
branches, most densely set in the ramuli, especially towards the margin. 
Colour of the recent frond brownish-olive, or dark brown, in drying 
green; of the granules both recent and dry green.” —Lyngbye. 
Odour in a recent state very offensive. 
One or other of the many forms of this species has been called 
Palmodactylon subramosum, Nag., but we have not, as yet, seen any 
true British representative of that genus. 
Plate X. fig. 4. a, natural size ; 4, portion magnified 400 diam. 
Genus 18. NEPHROCYTIUM. Wiig. (1849.) 
Cells oblong kidney-shaped, with a dorsal chlorophyllose 
vesicle, 2-4-8-16 associated in free swimming families sur- 
rounded by an ample oval or kidney-shaped tegument. Pro- 
pagation unknown. 
Only two European species, both of which have been found in the 
British Isles. Both are usually found together, and it is possible that 
hereafter they may be referred back to one species, as Nageli pro- 
posed. 
E 
