ScientificYntelligence. 
are those of the volume, as ought always to he the case, for con¬ 
venience and uniformity of reference. 
Dr. Engelmann deserves high praise and many thanks for taking 
in hand, one after the other, our difficult botanical subjects, con¬ 
centrating his attention upon them for a while, elucidating them to> 
the full extent of his opportunity, and leaving them in such a 
state that they can be easily understood, or readily followed up 
as occasion serves, by ordinary observers and collectors. His 
latest essay of this sort was upon Yucca. He passes from that 
to the analogous American genus, Agave , the “ American Aloe,” 
first distinguished from the old-world Aloe genus by Linnaeus, 
who gave them the .present name, Agave , “ because that word in¬ 
dicates something grand and admirable.” The headquarters of 
the genus are in Mexico, but a considerable number inhabit our 
southwestern borders, and one reaches well into the northern 
States. There are “ perhaps 100 species,”—possibly a high esti¬ 
mate, but the catalogues of cultivators give twice that number 
of names. Most of them are nearly unrepresentable in the her¬ 
barium, while in cultivation they seldom blossom. The century 
plant, A. Americana , may sometimes in our cool regions literally 
answer to its popular name: semi-centennial specimens at least 
are not uncommon. 
Dr. Engelmann first devotes a few important pages to the gen¬ 
eral structure and conformation of the trunk, foliage, inflorescence 
and fructification in the genus, and passes to a systematic arrange¬ 
ment and description of the N. American species as now known 
to him, and of a few extra-limital species upon which he is able to 
throw some light. They fall into three groups. 1. Singuliflorce , 
with flowers in a simple spike, a single one to each bract. Our 
northern A gave Virginica is the familiar representative: there 
are also A. maculosa of Texas, and A. variegata from just over 
the border, both in cultivation. 2. Geminiflorm , with a denser 
spike, a pair of flowers to each bract. Our species are arranged 
by obvious characters of the margin of the leaves, viz: with 
rough serrulate margins, A. falcata, n. sp.; with filamentose mar¬ 
gins, A. Schotti , n. sp., and A. parviflora , Torr.; with aculeate¬ 
toothed margins, A. hetearcantha , Zucc. (which is To^rey’s A. 
Lechuquilla ), and A. Utahensis , Engelm. 3. Paniculatm , the typ¬ 
ical Agaves or Century-plants, with paniculate inflorescence. There 
is a division with tube of the perianth much shorter than its lobes. 
Under this A. Newberry i, n. sp., is marked by the insertion of the 
stamens on the base of the tube. The others, with stamens borne 
in the throat, are A. deserti , n. sp., A. Parry i, n. sp. (doubtfully 
regarded by Dr. Torrey as a variety, latifolia , of A. Americana), 
and A. Antillarum Desc., with orange-yellow flowers, now eluci¬ 
dated from materials brought from San Domingo by Parry and 
Wright in 1871. The division with tube of the perianth shorter 
than its lobes, and bearing the stamens about its middle, contains 
a very striking species, A . Shawii , from the southwestern corner 
of California, which, having broad and deep-green leaves with a 
