a2, [ 300 } 
to be in the mountainous — of the tropics, especially in small islands, in 
which the proportion rises to 4, and even higher. Not ee the 
plains from the mountains, rips finds the proportion of ferns in the tor- 
rid zone to be 4: In ae rabia, India, New Holland, and shdil ‘Alive 
oon n the tropics) it is J : our American herbaria only indicate 2, Ap 
s are rare in the wide alloys and oad table-land of the Andes 
we were nein to reside a long time. In the temperate zone cule 
are 1, in France ,, in Germany, according to recent observations, 1... The 
group of ferns is sereteely rare on Alas, and is almost entirely absent from 
Egypt. [In a — — them ,/,; in Sweden, according to Wahlen- 
oe they are about ;4,.] the frozen zone ferns appear to increase: 
[There are none in Melville island. } 
** }4ONOCOT YLEDONES. 
“The denominator becomes progressively smaller in going from the 
equator to 62° north latitude; it again increases in still more northern score 
on the coast of Greenland, where Graminew are very rare. rown remarks 
that, in the list of pense plants, Dicotyledones are to Mo onocotyledoues 
4 to 1, or in nearly the scant ia ratio; and in Spit sym ees é 
ean be judged, wr proportion of Dicotyle eae appears to be still further 
increased. ‘This inversion was found to depend as much on the reduction 
of the proportion of Graminez as on the increase of certain dicotyledonous 
a et especially Saxifrageee and Crucifere. 'The flora of Melville isl- 
owever, very di flerent , Dicotyledones pein to Monoottrleiones 
as - to 2, or in as low a ratio as has any where been observed ; e the 
proportion of grasses is nearly double that of ony part of the world. asl rry’s 
Appendiz. he proportion varies from } to } in different parts of the 
tropics. Among 3,880 phanerogamous plants found in equinoctial ner 
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of ~ estate plants. According to Brow , this pro portion is in the 
old world (India, equinoctial Africa, “i New Holland) 4. Inde the tem- . 
perate zone it is found to be 4; France 1: 43; fina ; North 
America, gto to Pursh, 1: 44; He iy oe Naples 1: rhe ; “Sw itzer- 
_land 1: 4}; Great Britain 1:33; [Sweden 1: 3,°,; but in Sicily, according 
to Presl, it is 1: 5,,, which is much too high. | In the frozen zone 3. 
- “Gtumacea (that is to say, the three families of Junceae, Cyperacee, 
and Graminee united.)— Trop. 3,; Temp. 1; Frozen 3. This increase 
e and Cypera- 
rare, as compared with other erenogenee 
lants, in the temperate ee torrid zones... Comparing the species 
three families, we find that Graminew, Cyperaceee, and Jun neex, so in the 
tropics as 25, 7, 1; in the temperate parts of the old world as 7, 5, 1; yaa 
in the polar circle as 22, 23, and 1:. In Lapland there are as many 
minez as Cyperacee ; thence, towards the equator, Cyperaceze and _ Fae 
diminish much more than Graminee. ‘The form of Juncee almost disap- 
- -Pears in the tropics. 
pounce alone.—Zrop. z45: Temp. 75, (Germany ,',, France ,4,) 
. [Sicily abs ;] Brosenial #7 (Melville island ;..] 
: RACE alone.— Trop. America scarcely sx, Western racing 
loin 24) an Holland ; az} Lemp. perhaps 75, (Ger many. ;';, France 
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