Sok 
198 CRYPTOGAMIA ANTARCTICA. [Puegia, the 
I must offer some apology for omitting a class of organisms which have been investigated, and considered 
of vegetable origin, by Prof. Ehrenberg, and which are almost equally abundant in the Antarctic Ocean with the 
Diatomacee, whether on the surface or at the bottom of the sea: these are the Phytolitharia, Ehrb. I am not 
aware of the precise limits of this Order, and of many of the genera composing it; but from casual allusions, 1 
gather that the term Phytolitharia is a conventional one, employed to designate the siliceous and other inorganic 
particles, deposited in plants of a higher structure. Thus, Lithodermatium is a genus whose species are represented by 
modifications of the siliceous epidermis of one or many species of Equisetum; and-the Lithostylidia are the siliceous 
cells of Graminee *. It is not my object to discuss in this place the expediency of constituting such orders, 
genera, and species. The total absence of Equiseta from the Antarctic Flora, and of Graminee or other pheenogamic 
plants from any position within 700 miles of Victoria Barrier where the Phytolitharia abound, renders it in the 
highest degree improbable that the latter should be of vegetable origin. t 
A few remarks on the phases and situations under which these curious vegetables occurred, will not be mis- 
placed here, especially as I have little to add to what is already known of their habits. and organization. 
Scattered on the surface of the ocean, the Antarctic Diatomacee were seen ‘connected in filaments, or resolved 
into thesimple frustules, of which they are composed. When entire, they shewed no signs of motion or irritability. 
The grumous or granular contents of the cells were yellow under the microscope ; but in mass the same species 
assumed an orange-brown, or burnt Sienna colour; the intensity of which depended on the denseness with which 
they were packed together. 
The various means employed for ‘selecting the ‘species varied according to circumstances, as the following 
enumeration of the processes pursued will show. 1. Sea-water was filtered through closely woven bibulous paper 
(filter-paper), which latter was folded, dried, and carefully put away. If a certain measure of water be always 
thus treated, an approximate knowledge of the abundance and scarcity of the various species and genera occurring 
at different positions, may be gained. 2. The scum of the ocean almost invariably contains many species entangled 
in its mass; it was preserved in small phials, well secured. 3. A tow-net of fine muslin, used when the 
vessel’s rate does not exceed two or three knots, secures many kinds, which may be washed off the muslin, and 
collected on filter paper. 4. The stomachs of Salpe i and other (especially of the naked) mollusca, invariably 
contain Diatomacee, sometimes several species. These Salpe were washed up in masses on the Pack ice, and 
in decay they left the snow covered with animal matter impregnated, as it were, with Diatomacee: the religwie 
were preserved in spirits. 5. The dirt and soil of the Penguin Rookeries, and especially their Guano, abound in 
Diatomacee, perhaps originally swallowed by the Salpe and Cuttle-fish, which themselves become the prey of the 
Penguins. 6. Ice encloses Diatomacee: they are deposited on the already formed ice by «the waves, \or 
frozen into its substance during calm weather, when the upper stratum of water rapidly congeals. Ice, so formed, 
generally breaks up by the swell of the.sea into thin angular masses, which become orbicular by attrition, whence 
the name Pancake-ice. The Pancake-ice was-often seen a few hours after a calm, covering leagues of ocean, and 
uniformly stained brown from the abundance of these plants. It was taken in buckets, and when removed 
from the water appeared perfectly pure and colourless. On melting, however, it deposited a pale red cloudy preci- 
pitate, excessively light, consisting wholly of Diatomacee. This precipitate was bottled on the spot, and proved 
* See Ehrenberg, in Schrift. Berlin Akad., June, 1841. 
T On the contrary, I cannot but suspect that some of these Phytolitharia are the remains of Crustacea, and 
especially the-silicéous (?) particles, which occur in'the tunics of naked Mollusca. 
+ I do not remember to have examined the contents of the stomach of any Salpa between the latitudes of 
the N. Tropic and the 80? S., which did not contain the remains of Diatomacee. Dictyocha aculeata was universally 
found in the stomachs of those I opened when off Victoria Land. 
