shows eight tubes, surrounding a narrow cavity. Capsules ovate, formed 
out of one of the pinnules, supported on a short stalk, and containing a 
tuft of pear-shaped spores. e¢vaspores ranged in a single series, in swollen 
pinnules. Colour, when growing, a fine, clear red; assuming, in drying, 
more or less of brown; and, if dried without steeping in fresh water, im- 
parting a brown stain to the paper. Swéstance rather rigid, imperfectly 
adherimg to paper. 
Iam happy to have this opportunity of returnmg my best 
thanks to the Rev. D. Landsborough, of Saltcoats, for a series of 
most beautiful specimens of this charmmg Alga; by much the 
finest which I have ever seen. The larger figure m our plate is 
taken from one of this gentleman’s specimens ; the smaller from 
one of the usual size. ‘The difference is strikingly in favour of 
the Scottish plant. To Mr. Landsborough I am also indebted 
for the first capsule-bearmg plant which I possessed; this kind 
of fruit being of more rare occurrence than tetraspores. 
Polysiphonia parasitica is, | believe, a much more generally dis- 
tributed species on our shores, than is commonly supposed ; but 
owing to its habitat, it very frequently escapes detection. Unless 
it be obtamed by dredgmg, which, in favourable localities, is, 
perhaps, the most certain means of procuring specimens, it can 
only be had by examining the submersed perpendicular sides of 
ledges of rock, at the extreme limit of low water. ‘These ledges 
are frequently coated over with a thin spreading MJelobesia, or 
with the base of Corallina officinalis. On these Corallines the 
Polysiphonia grows. I once found it on the stem of Laminaria 
digitata, but it was of very small size. 
This species is very closely related to Pol. pennata of the 
Mediterranean, and to P. dendroidea, a beautiful Peruvian Alga. 
These plants have a adit more resembling that of the genus 
Rytiphlea, but in their technical characters they do not accord 
with that group; and there is nothing to distinguish them in 
structure from other Polysiphonie. In all three the frond is 
slightly compressed ; but this character is not peculiar to them. 
Fig, 1. PoLysIPHONIA PARASITICA, growing on Melobesia lichenoides :-—of the 
natural size. 2. Portion of a pmna. 3. Pinnule with ¢e¢raspores. 4. 
Branchlet with a capsule. 5. Portion of the frond. 6. Transverse section: 
—-all more or less magnified. 
