OS Ie Ps a aE + 
i ieee ao 
NED J AEA pe GY Te Pee, RE a ae 7 
mg ee Oe ae a eT ee) ae oar i eee ee 
ee eae Gt yee se e 
ee 
3 ee 
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Botany and Zoology. 339 
, ame wo e said 
not that the frond looks diminutive. The three Asplenia make a 
fine plate. But the figure of A. parvulum is stiff: we never saw 
it growing bolt upright, and the difference in size between this 
and the other two is not made antes manifest. A somewhat 
mer. , ANDE 
ATON, Fase. III. The eed: Fascieuls of. this asbatien of 
North American Algz has just been issued. It consists of only 
thirty specimens, covering Fea Bal fe ee and one variety. 
But as most of the species are large plants, the paper used is of the 
folio size of most American herbariums. Twenty of the Al 
e he 
23 Callophyllis laciniata on the coast of Madero but then 
. 129 j 
6. On the Black Mildew of Walls.—Professor Lemmy remarked 
that in the number of “ Hardwicke’s Science Gossip” for August, 
gs this evening, — of er article by Professor Paley en- 
ae “Is the Blackness . Paul’s merely the effect of 
ly du 
flourish on limestone and in situations unaffected by the direct 
rays of the sun. Professor Leidy continued, that his attention 
had been called a number of years ago to a similar black appear- 
ance on the brick walls and granite work of houses in narrow 
Shaded streets, especially in the egies of the Delaware River. 
oticing a similar blackness on the bricks above the windows of 
. brewery, from er there en a constant escape of watery 
vapor, in a more central portion of the city, he was led to suspect 
that it was of a nS, nature, On examination, the black 
