544 THE AMERICAN NATURALIST. (VoL. XXXIII. 
and its results, instead of on the structure of the mature cystocarp, as 
was Agardh’s scheme. Schmitz’s plan has the disadvantage that the 
data for its application are known in only a small proportion of the 
algæ; the great majority have to be assigned their place by analogy 
with the few of which it has been possible to study the development 
thoroughly; and already new observations threaten to reopen what 
Schmitz considered settled questions. 
Agardh’s system was more convenient, in that we knew the cysto- 
carps of much the greater part of the red alge, and might reasonably 
hope to find cystocarps in the few species where they were still 
unknown. But the chance is small of an opportunity to follow the 
stages from trichogyne to cystocarp in an alga from some remote part 
of the world, of which only a few sae are known, and those 
washed up from deep water. 
The present section of the work is devoted to a review of the 
Delesseriaceze, of which the known species have much increased 
since the publication of part one of the volume in 1876. The limita- 
tions of the family are the same as before, but the subdivisions are 
changed, and several new genera are founded at the expense of the 
old genera Nitophyllum and Delesseria. The cystocarpic fruit is 
practically the same in all, and the characters of the tetrasporic fruit 
are used only for specific distinctions ; all the species have the form 
of a flat membrane, and the distinctions are made by the greater or 
less number of layers of cells, the difference in size or shape of the 
cells of the different layers, and the presence or absence of raised 
mid and lateral ribs, or of veins, not elevated but formed by cells of 
distinctive form. Several new American species are described from 
Florida and from the Pacific coast, 
We are sure all algologists will join in the hope that this, the latest 
in the author’s long series of contributions, will not be the last. 
F. S. COLLINS. 
Greenland Algæ.'— It is a rather curious fact that there is hardly 
any part of the American coast with whose alge we are as well 
acquainted as we are with those of Greenland. A number of investi- 
gators have contributed to our knowledge of this region, but much 
the largest share is due to the author of this work. In a former 
work on the same subject ° he gave what seemed a very full account 
1 Rosenvinge, L. Kolderup. Deuxième Mémoire sur les Algues Marines de 
Groenland, Meddelelser om Groenland,.XX. Copenhagen, 1898. 
2 Groenlands Havalger, Meddelelser om Groenland, III, 1893. 
