(144) 
simplicibus. Thallus fruticulosus, erectus, solidus, squamulis gran- 
ulisve, in ramulos corallinoideos nunc abeuntibus, plus minus 
vestitus (podetia) horizontali granuloso 1. seepius evanido. 
This well marked natural genus might be supposed more distant from 
Cladonia than it really is, were it not for the little group of curiously 
intermediate lichens constituting Pilophorus, Th. Fr. The species of 
Stereocaulon are especially mountain plants; and distributed, in such 
situations, throughout the earth. About three quarters of the twenty 
odd described species inhabit however the mountains of the intertropical 
regions, and the centre of distribution may therefore well appear, as it 
did to Fries (8. O. V. p. 248) whose remark is fully illustrated by the 
monography of Dr. Th. Fries, as ‘magis tropicum.’ All the well ascer- 
tained European species occur in North America, except, as yet, S. nanum; 
and several others, found in Mexico, extend, it is possible, farther north. 
Among those who have contributed to our knowledge of Stereocaulon, 
Floerke, Fries, and Laurer should be especially named; these writers 
having satisfactorily determined the important forms of the northern 
hemisphere. The illustration of the less known, tropical species was left 
for the more recent monography of Dr. Th. Fries; and the still later 
revision of the genus given in the Synopsis of Dr. Nylander. This work 
was the first to attempt a full exhibition of the still imperfectly under- 
stood ‘ cephalodia’ ; but most important additions have since been made 
to our knowledge of these structures in the cited memoir (Beitr. 2. Kenntn. 
d. Cephalodien) of Dr. Fries. 
S. ramulosum, Ach., the collective name of a group of tropical and 
austral forms, which later writers have variously discriminated, is credited 
by him to North America, as it is also by Muhlenberg (Catal. p. 106) and 
may be what Dr. Fries (1. c. p. 30) has indicated, under his S. argus, as 
sent to Swartz by Menzies. The group appears to be well represented 
in Mexico, but no member of it is known to me as occurring within the 
United States; nor was there any Stereocaulon in the collection of his 
lichens with which the late Mr. Menzies favoured me. 
S. spherophoroides, Tuckerm. (Th. Fr. l.c¢. p. 44. Nyl. Syn. 1, p. 234) 
an inhabitant of the Canary Islands, is cited by Nylander, 1. c., on the 
authority of the herbarium of Mr. Lenormand, as occurring also in 
‘Carolina’; a locality from which I have never received it. 
S. nanodes, Tuckerm. Suppl. 2, 1. c. p. 201 (Nyl. Syn. p. 251) is found 
on rocks along water courses in the White Mountains. The granules in 
this species become squamiform, and the tips of the branches assume 
then an aspect often not a little suggestive of the extraordinary lichen’ 
following.——-S. (sub-gen. Phyllocaulon) Wrightii, Tuckerm. Suppl. 2, 1. 
c. p. 202, was found by Mr. Wright on anisland of Behring’s Straits; but 
the apothecia are unknown. This plant is comparable also with the 
equally sterile S.? pulvinatum, Ach., of the Cape of Good Hope (Drége 
