GEOGRAPHICAL DISTRIBUTION OF THE EQUISETACEX. 323 
in Mexico and Peru. Six species are peculiar to South America, of 
which, however, only two enjoy a large geographical distribution, viz. 
E. giganteum, Linn., spread from the West India Islands to the south 
of Chili, and Æ. Bogotense, Humb. et Bonpl., to be traced from Guatemala 
to the same southern position as the last-named species, and repre- 
senting in South America. F. palustre, Linn. (which is not found in 
., that country), and to which it is closely allied. It is very singular 
‘eat hat even the shortest stems of Æ. Bogotense never have a central cavity. 
Of the other species, Z. zylochetum, Milde (stem ten feet high and an 
inch in diameter), is found in Peru, and Z. Brasiliense, Milde (almost 
às large as the preceding, and entirely without branches), exclusively in 
Brazil, whilst the most gigantic of all Zguiseta (E. Martii, Milde) has 
been discovered both in Brazil and Peru, and E. Schaffneri, Milde, as 
“already mentioned, in Peru and Mexico. Curiously enough we also 
encounter a South European species (E. elongatum, Willd.), with very 
distinct forms, which has been communicated to me from Mexico and 
Chili. On proceeding northwards, we find in Mexico five species, of 
which two are peculiar to the country, the gigantic and fine E. myrio- 
chetum, Cham. et Schlecht. and the Æ. Mexicanum, Milde, a plant 
allied to E. elongatum, Willd. We meet besides F. Schaffneri, Milde 
(n habit resembling Z. Zimosum, Linn.), E. elongatum, Willd. and F. 
robustum, A. Braun (allied to E. hiemale). In California we have Æ. 
Braunii, Milde, a species very close to £. Ti elmateja, Ehr., and nowhere 
else as yet observed. In the United States we find, with the exception 
“Of E. pratense, Ehr., confined to Greenland and Labrador, nearly all the 
European species, viz.-E. arvense, Linn., E. sylvaticum, Linn., E. palustre, 
Linn, Z, limosum, Linn., E. hiemale, Linn., E. variegatum, Schleich., 
| Mid P. Scirpoides, Mich. There are, besides, two other species, E. 
|  fohwstum, A. Braun (found between 20? N. lat. and 39? N: M 
| ad E. lævigatum, A. Braun (ranging between 30? N. lat. and 39 
: N. lat), both common on the banks of rivers. The most southern 
1 locality for E. hiemale, Linn., is California. Most species, viz. E. 
| tense, E. sylvaticum, E. palustre, and E. limosum, are met with as far 
South as Virginia, lat. 36° N.; E. Telmateja, Ehr., seems to be confined 
1 to the neighbourhood of Lake Erie and Lake Superior. Hooker and 
|  Amott (Bot. Beechey, 1841) record it also from San Francisco, in 
Li Upper California ; but as we know from thence E. Braunii, Milde, which 
is very like Z, Telmateja, we may assume that the authors a 
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