PALMELLACEA. 15 
Palmodictyon viride. Kutz. Tad. Phy... ¢. 31,f. 1. 
Thallus mucous, irregularly reticulate, about the thickness 
of a hair, greenish ; cells biserial, with a very thick homoge- 
nous tegument. 
Sizz. Cells without tegument, :0075-'009 mm., with the 
tegument °025--04 mm. (Radh.). ° 
Rabh, Alg. iii. 87. Kutz. Phy. Germ. p. 155. 
In ditches, canals, &c., attached to stones, twigs, &c. 
Recently found by Mr. E. Parfitt near Exeter, of which he gives the 
following account :—“ The plant, where it has sufficient room to develope 
itself, spreads over the bottom, in water about six inches deep; beyond 
this it comes in contact with Hlodes canadensis, over which it creeps, and 
extends its growth from branch to branch into deeper water. In this 
extension it has first the appearance of a Conferva, which I at first took 
it to be; bat the moment I touched it, after taking some from the 
water, I found from the soft slimy feel that if a Conferva it was new to 
me, and the microscope soon revealed the true character. When the 
plant grows on the bottom it shows one continuous green membrane, 
stretched tight over the bottom, but when it comes ‘in contact with other 
plants it throws out filaments, the thickness of which is difficult to make 
out on account of their adhesive nature; for wherever they touch it is 
matter of impossibility to separate them. The membrane forming the 
filaments is structureless, but the spherical cells, which form more or 
less moniliform threads, sometimes running in parallel lines, at other 
times forming an irregular net-work on the inside of the filaments. 
These cells sometimes divide into two portions, at others into four, and 
in most of the mature cells may be observed four cellules.”—Grevillea, 
iii., p. 29. 
Plate VIII. fig. 2. u, portion magnified 200 diam.; 6, fragment 
magnified 400 diam. 
Palmodictyon rufescens. Kutz Spec. 234, 
Is usually referred here on the faith of the remark by Kutzing, that it 
was found at Aberdeen by Dr. Dickie. Upon enquiry of Dr. Dickie we 
learn that he knows nothing of the species. He says, “ Palmodictyon 
rujescens is unknown to me, many years have passed since I corres- 
ponded with Lenormand, and I do not remember receiving any note 
from him regarding it. Kutzing (Spec. 234) is responsible for the name. 
I cannot find in my collection anything so named, neither do I re- 
member where the so-called material was collected.” Under these cir- 
cumstances it is useless repeating the name in connection with British 
Alge. 
Genus 10. TETRASPORA. Link. (1810) 
Thallus gelatinous, membranous, or submembranous, in the 
beginning a short sac, afterward expanded; cells globose or 
angular, more or less distant, but associated in a single stratum 
into large families. Tegument thick, very rapidly diffluent into 
ahomogenous mucous. Division in two directions in the same 
plane. 
