30 RICCIACEAE 
vorable for this purpose Heidenhain’s iron-haematoxylin method 
(Zeit. f. wiss. Mik. 9: 204. 1892. Lee, Microtomist’s Vade- 
Mecum, 175. 1896 [4th ed.]). The only European specimen of 
К. щетейа (Husnot, Hep. Gall. 96) which we have subjected to 
this treatment shows the same peculiarity even in the soaked-out 
dried material. AR. Campéclliana, especially in forms with numer- 
ous oil-bodies, occasionally exhibits something which seems 
similar at first sight, but in this the epidermal cells which take the 
haematoxylin stain occur irregularly, are filled with a more gran- 
ular substance, and appear to be simply cells with oil-bodies like | 
those found elsewhere in the thallus. 
Herr Stephani, who, we are informed, has had the opportunity 
of examining the original specimen of Riccia aggregata Underwood 
describes* it as dioicous ; we, however, on makinz microtome sec- 
tions of the same type material, find it clearly monoicous. Herr | 
Stephani describes the “frons” of А. nigrella as “ subtriplo latoir | 
quam crassa "t while that of R. aggregata is “ vix duplo latior фиат | 
alta,” but on comparing sections of French and Italian specimens 
of R. nigrella with sections from corresponding regions іп Ж. 
aggregata, we find the differences slight and, we believe, of no 
specific significance. The length of the ‘frond, the number of 
times its forking is repeated, and the form of the terminal lobes 
are variable characters in both the Californian and the European 
specimens, and, either separately or combined, afford no reliable 
grounds for specific distinctions. | 
9. КіСсІА CATALINAE. Underw. Bot. Gaz. 19: 275. 1894. 3 
thin and exhibiting suggestions of a wide-meshed areolation as if 
from interior air-chambers, the cells of the dorsal surface large, 
thin-walled, and indistinctly defined (at least in soaked-out | 
herbarium material), the older parts of the thallus spongiose- | 
alveolate from the bursting through of the air-chambers to the | 
upper surface, root-hairs nearly or wholly smooth within; the | 
* Bull. Herb Boiss. 6: 342. 1898. 
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