ХПІ. On the Minute Structure апд Mode of Growth of Ballia callitricha, Ag. (sensu 
latiori) By W. АксКЕв, F.R.S., M.R.I.4. Communicated by У. Т. TutsEUTON 
Dyer, MA., FLS. 
(Plates XXVIII. & XXIX.) 
Read June 15th, 1876. 
SOME small fragments only of this alga (mixed with some of the freshwater algæ 
enumerated by me in the Society's * Journal, No. 87) were at first met with in gatherings 
made by Mr. Moseley, of H.M.S. ‘Challenger,’ in Kerguelen's Land. They were much 
macerated and wholly deprived of colour, very few of the cells indicating the presence of 
contents, and the cellular structure being rendered hyaline. I submitted such a specimen 
to my friend Prof. E. Perceval Wright, who, aided by one at same time given to me by my 
friend Mr. Gilbert Sanders, identified itas a form of Ballia callitricha ; and on comparing 
it with perfect examples in the herbarium of Trinity College, Dublin, the diagnosis was 
sustained. However, on a closer search of Mr. Moseley's collection, I afterwards found 
that it contained, in addition to the isolated and broken-up fragments, some complete 
and characteristic examples of our Ballia; so that the identification was complete. I was 
much pleased to find these latter in the gathering, as they afforded, of course, much more 
suitable subjects for study—though even the first small shreds which I had noticed not 
only presented examples of a minute and apparently characteristic structure within the 
cells, which thus seems to possess some histological interest, but they likewise showed 
some interesting points relating to the outward configuration and mode of growth of this 
alga, all of which, so faras I can see, seem to have hitherto remained unnoticed. 
The fact that a Rhodosperm should have occurred in a collection made from fresh 
water and containing characteristic freshwater forms, possibly does not in reality possess 
that amount of interest which at first glance might seem to appertain toit. It is true 
that the aleze of marine type which strictly belong to the fresh waters are very few, and 
they are but of small dimensions and humble habit, and not at all striking. Such аге, 
for instance, Chantransia, Bangia, Hildenbrandtia. Та Ballia we have a type, indeed, 
more elevated, more pronounced, than any of these, an elegantly configurated and 
compoundly branched form ; but I should be much inclined to suppose our specimen was 
à mere marine waif (possibly blown in by the wind); or it may have been taken from а 
site to which the sea had only occasional access (and cast in by the surf)*. The more 
“Таш further indebted to Prof. Perceval Wright for drawing my attention, however, to a record by Dr. Мов- 
tagne (addressed to the Academy of Sciences, May 13, 1850) of the fact that М. Lemprieure had eolleeted in the 
running waters of Guiana three species of Bostrychia, one Gymnogongrus, and two of Ballia. These were found 
either in rivulets of the mountains of Mahuri (** 80 kilo." from Cayenne) or in the watercourse of the ereek Gravier, 
in the Kan mountains (“40 kilo." from the sea, and at an elevation of 100—150 metres) The waters presented no 
: trace of salt; and their elevation precluded all thought of any flow back of the tide bearing germs of these plants. Of 
_ the Ballia examples, which were minute forms, one (Ballia pygm«a, Mont.) grew attached to а Batrachospermum, 
the other (B. lemprieurii, Kütz.) to stones. 
