482 The American Naturalist. [May, 
Alectoria. 
A. ochroleuca rigida Fr. On earth. Orizaba. Common. (Smith 1). 
A. fremontii Tuckerm. Trees. Orizaba. (Smith 4). Often mixed 
with Usnea cavernosa, 
Theloschistes. 
Th. flavicans (Sw.) Mill. Abundant on trees. Orizaba. (Smith 41). 
This is certainly distinct from Th. chrysophthalmus and should 
be maintained as a species. 
Parmelia. 
P. perlata (L.) Ach. “Growing on rocks near warm springs,’ Ag- 
uascalientes ; Orizaba. (Smith and Bruner 27). 
The thallus is not always as smooth as is common in this species. 
P. latissima Fee. Trees. Orizaba. (Smith 28). 
Thallus sometimes isidiophorous. 
P. perforata (Jacq.) Ach. Trees. Orizaba. Common. (Smith and 
P. perforata hypotropa Nyl. Trees. Orizaba. (Bruner 30). 
P. cetrata Ach. Oak trees N. W. slope of Mt. Orizaba. Alt. 10- 
12,000 ft. (Smith 31). 
P. revoluta (Floerke) Nyl. Trees. Orizaba. (Smith 33). 
P. kamtschadalis americana (M. & F.) Nyl. “On oak trees N. W. 
slope of Mt. Orizaba.” Alt. 11,000-12,500 ft. Very plentiful. 
(Smith 36). 
P. caperata (L.) Ach. On oak trees at Jalapasco. Alt. 10,000 ft. 
Rocks, Aguascalientes. (Smith 34 
P. conspersa (Ehrh.) Nyl. Rocks. Orizaba; Aguascalientes. Com- 
mon. (Smith 35). 
Some of the specimens from the latter locality belong to the f. 
isidiata Anzi. 
cia. 
Ph. hypoleuca (Muhl.) Tuckerm. At bases of trees sang moss. 
Orizaba. (Smith and Bruner 62). 
Ph. comosa (Eschw.) Nyl. Trees. Orizaba. Common. (Smith 38). 
Ph. leucomela (L.) Michx. Trees. Orizaba. Abundant. (Smith 
Ph. lencomela angustifolia M. & F. With the preceding. (Smith 
40). 
Ph. stellaris (L.) Tuckerm. On oak trees at Jalapasco and else- 
where on Mt. Orizaba. Common. (Smith and Bruner 42). 
It is often difficult to separate this from the following species. 
