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doubtless, also, Melocactus, seeds of which, however, have not been ex-O 
amined by me; and Echinocactus, mostly with a curved embryo. TheH 
second class includes Echinocereus, with a nearly straight embryo, and 
very short cotyledons; Cereus , with a curved embryo, and foliaceous in- 1 
cumbent cotyledons, (probably also Echinopsis and Pilocereus,dnd per-i 
haps Phyllocactus and Epiphyllum;) Opuntia, with a circular or spiral I 
embryo, (circular and with a larger albumen in all Opuntiae cylindraceae; | 
spiral and with a much smaller albumen in all Opuntiae ellipticae , exam- j 
ined by me,) and very large cotyledons. Rhipsalis and Pereskia may | 
also belong here, but were out of my reach. 
The flowers of all the species belonging to the first class, with the doubt- | 
ful exception"of «ome Mammillaricfe, make their appearance on the growth 
of the same year. Those of the second class produce the flowers always 
upon the growth of the next preceding or former years. The first class 
may, therefore, be distinguished by the name of Cactaceae parallelae , (from 
the direction of the cotyledons,) or C. apici florae, (from the position of the 
flowers.) The second class can be named, in a corresponding manner, 
Cactaceae contrariae , or C. laterifloraSi 
Echinocereus is principally distinguished from Cereus proper by its low 
growth; its short, more or less oval stems, which are frequently branching 
at base, 4 and thereby cespitose; by the diurnal flowers, with short,tubes; 
by the nearly straight embryo, with short cotyledons. From Echinopsis , 
to which some species have been referred, it differs also by the short-tubed 
diurnal flowers, and by the numerous filaments bein^adnate to the lower 
part of the tube. For further particulars compare the note 7. The spe¬ 
cies of Echinocereus inhabit Texas and the northern parts of Mexico, 
ft .-X where Cerei proper are very rare. They extend even farther north than 
p , i the Echinocacti, but appear to be excluded from the old limits of the Uni- 
s > i * J ted States, where the cactus family is represented only by some Opuntiae 
and Mmnmillariae. The $outhern limits of the Echinocerei are un¬ 
known to me, but I doubt whether they extend far in that direction; the 
nearly-related Echi\iopses, on the contrary, appear to be exclusively inhab¬ 
itants of South America, especially the La Plata countries. 
As I am speaking of the geographical distribution of the Cactaceae, I 
may as well add here that Mammillarme were found throughout the 
whole extent of Dr. Wislizeiius’s tour, and that at least four species occur 
in Texas. Echinocacti were observed only south of Santa Fe, and from 
there to Matamoros, but none on the highest mountains, which were occu- 
* pied by Opuntiae 7 Mavnmillariae, and Echinocerei ; two Echinocacti have 
been found in Texas. Only two species of true Cerei were seen; one of 
a peculiar type about Chihuahua, and another near the mouth of the Rio 
Grande, which does not appear to differ from the wide-spread C. variabilis, 
Pfeiff. Opuntiae ellipticae well as cylindraceae y were observed from 
New Mexico to Matamoros, and species of both are also found in Texas. 
Melocacti, Phyllocacti , and other genera of Cactaceae , not mentioned 
above, were not met with. 
The notes and collections of Dr. Wislizenus confirm the opinion of that 
acute.observer and successful cultivator of Cactaceae , Prince Salm-Dyck, 
viz* that most species of this family have a-very limited geographical 
Y Opuntia Q m ° St Strikil3 S exce P tion being those belonging to the genus 
