650 NATURAL HISTORY MISCELLANY. 
as “fixed by the base, introrse.” The first volume of the ‘‘ Genera 
North American Illustrated” appeared in 1848. This season I 
have, for the first time, had the good fortune to see both P. palus- 
tris and P. Caroliniana in flower, in the Botanic Garden of Har- 
vard University, the former blossoming at the beginning, the latter 
at the close of August. The difference between the two species 
‘<in this respect” is obvious. 
In P. palustris, the anthers are certainly extrorse as to inser- 
tion; but the line of dehiscence lateral, with introrse rather than - 
extrorse tendency. 
P. Caroliniana, the anthers are quite as much introrse as 
extrorse as to insertion, and truly introrse for dehiscence. <A 
transverse section removes all doubt, showing the connective or 
solid part to be posterior, and the anther to be as truly introrse es 
possible.— A. Gray, American Journal of Science. 
GEOGRAPHICAL DISTRIBUTION or SEA — — Under this ti- 
tle, Dr. P. Ascherson gives an account, in a recent number of 
Petermann’s “ Geographische eee ” of the distribution 
of the species of flowering plants native to sea water. Of these he 
enumerates twenty-two, belonging to eight genera, and two natural 
orders. The area of each species is generally very limited, its 
distribution being mainly dependent on the present condition of 
the sea in which it is found, as to temperature, etc. Those which 
grow in temperate regions are frequently represented by closely 
allied species in tropical seas. Although the Isthmus of Suez is of 
comparatively recent geological date, the nine species found in the 
ed Sea are entirely distinct from the four species of the Mediter- 
ranean, and, with one exception, belong to different genera. A 
good map accompanies the paper.— A. W. B 
Tue STRUCTURE oF Boa Mosses. — Dr. R. Braithwaite, the 
highest authority in England on the mosses, has published in a 
recent number of -the ‘Monthly Microscopical Journal,” an ac- 
count of the structure of the Sphagnine or Bog-mosses. Dr. 
Braithwaite follows Schimper in considering them as a distinet 
order of the same rank as the true Mosses and Liverworts; the 
muscal alliance being thus formed of the three orders Bryin@, 
Sphagnine and Hepaticine. The spore of the bog mosses does 
not, on germination, produce the much-branched confervoid pro- 
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