(38 ) 
also strictly marginal, and the whole plant indeed not a little resembles 
the species last named. A similarly, but much less dwarfed state of P. 
canina, with short fertile lobules, occurred at the same station; where P. 
venosa, perhaps always less impatient of cold, was particularly fine. The 
range of the genus is northern, and the eight or nine best-known species 
are common to Europe and North America. P. canina, P. polydactyla 
(as compare Nyl. 1. c.) and probably others, extend also widely through 
the warmer regions of the earth, where the suitable conditions exist. 
A thinner, glaucous form of P. aphthosa, in which the veins are pecu- 
liarly conspicuous beneath (v. minor, Tuckerm. ecs. n. 102) is common 
and noteworthy in the New England mountains; and Mr. Wright col- 
lected it, on mountains, in Japan. ——In astill more remarkable condition 
of P. canina (v. spongiosa, exhibited, but not satisfactorily at No. 103 of 
the just cited collection) the under side is at length most densely spongy- 
villous, the veins remaining visible only at the circumference of the thallus, 
and the thickness of the soft cushion of intertangled fibrils exceeding 
at length 2™™ This variety has only occurred in subalpine regions of 
the White Mountains. And the same regions furnish also, (on moist 
rocks) a reduced but fertile state (v. sorediifera) referable to P. canina 
by the under side and the pubescence and colour of the upper, but readily 
distinguished by its rounded, grey soredia; which are well comparable, 
though perhaps more often central, with those of Sticta limbata. The 
lichen approaches the v. spongiosa in its often dense villus beneath, but 
is alwayssmallish. Mr. Wright found it on ‘banks’ in islands of Behring’s 
Straits. ——Southward a still smaller plant occurs (South Carolina, on 
moist rocks, Mr. Ravenel; California, Mr. Bolander) scarcely reaching 
two inches in diameter, but in other respects, unless it be the more naked 
under side, agreeing closely with small specimens of the other. To this 
last I cannot but refer Peltidea erumpens, Tayl. in Hook. Lond. Journ. 
Bot. 6, p. 184, from clay banks in Ireland; nor do Lindig’s specimens of 
Peltigera leptoderma, Nyl. (Lindig Herb. N. Gran. n. 2559) appear to 
differ at all from the Carolina ones. The spores of both states of v. 
sorediifera, as well as those of v. spongiosa, accord satisfactorily with 
those of the type to which the lichens are here referred. To the southern 
condition of the first named of these varieties, another, —P. canina, v. 
spuria, Ach., excellent specimens of which have been sent to me by Mr. 
Ravenel and Mr. Bolander, approaches often near, and seems to offer 
indications (as also does my copy of Moug. & Nestl. n. 837, & Rabenh. 
Lich. Eur. n. 421, ¢) of soredia, but the thicker thallus is comparable 
rather with that of P. rufescens, to which Nylander refers the lichen. 
Very beautiful specimens of this variety, combining the habit and texture 
of v. spuria with the soredia of the other, were collected by Mr. Wright 
in Japan.—P. canina is typically tomentose above, but tropical speci- 
mens (Island of Juan Fernandez, Herb. Mont.; Venezuela, Fendler) are 
smoother and at length glabrous, and this condition, which is also thinner 
