ENGELMANN—ADD. TO CACTUS-FLORA OF U. S. 203 
ters left us, to be used in the arrangement of the very large 
number of species of this protean genus, to which several 
lately established genera have to be reduced. The following 
disposition is suggested: 
1. Cereiflore regulari, plerumque breviore ; staminibus tubo gra- 
datim adnatis. 
Echinocereus, Eng. 
Acanthocereus. 
Lepidocereus^ Eng. 
Pilocereus, Lem. 
2. Cereiflore sape obliquo, plerumque longiore; corona staminum 
exteriorum erectorum a ceteris gradatim adnatis plus minus decli- 
natis discreta. , 
Echinopsis, Ziicc. 
Eucereus. 
Phyllocactus, Link. 
Disisocactus, Lindl. 
Under the name Acanthocereus I comprise the species of 
this division with spiny fruit, but not belonging to Echino- 
cereus ; it is probable that Pfeilfera, Salm, is only a diminu¬ 
tive form of Acanthocereus. Lepidocereus, to which many 
tropical species must be referred, and also a few which lately 
have been classed with Pilocereus, is distinguished from the 
latter by the uniformity of the fertile and sterile branches and 
areolae, while in Pilocereus the fertile areolae are closer to¬ 
gether and densely beset with' bristly spines or long wool. 
Eucereus, in a more restricted sense than Miquel has used it 
in his Genera, or jjf in the Synopsis, would comprise the largest 
number of Cerei of the second division, of very different ex¬ 
ternal shape, and would probably have to be again subdivided 
when we get to know more of the fructification of the differ¬ 
ent species. Neither Echinopsis nor Phyllocactus do in their 
flowers differ from Eucereus, and Disisocactus is but a de¬ 
pauperate Phyllocactus, with scarcely more than the crown 
of stamens left, a few single ones representing the great mass 
of inner stamens of the allied sections. I am as yet unde¬ 
cided whether Epiphyllum, as restricted by Prince Salm, has 
also to be united with Cereus or not; the fasciculated de¬ 
clined stamens spring from the whole tube; the exterior 
ones form no crown, but the innermost ones are separated 
from the rest, and form, with their confluent bases, a kind of 
vault, which is arched oyer the base of the tube. I have had 
no opportunity to examine fruit and seed. 
I am not sure whether the true Cereus variabilis is also 
found on the Lower Rio Grande. A specimen in Mr. Goebel’s 
horticultural establishment, said to come from that region, 
has repeatedly flowered and borne fruit; the flowers opened 
in May, and the fruit ripened after 10 or 11 months; flower 
9 inches long, white, open only at night; ovary angular, with 
