ENGELMANN — ADD. TO CACTUS-FLORA OF U. B. 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. CereiJloreregulari,plerumquebreviore; staminibus tubo gra- 

 dalitn adnatis. 



Echinocereus, Eng. 

 Acanthocereus. 

 Lepidocereus, Eng. 

 Pilocereus, Lem. 



2. Cereiflore sape obliquo, plerumque longiore; corona staminum 

 exteriorum erectorum a cceteris gradatim adnatis plus minus decli- 

 natis discreta. 



Echinopsis, Zucc. 

 Eucereus. 



Phyllocactus, Link. 

 Disisocactus, Lindl. 



Under the name Acanthocereus I comprise the species of 

 this division with spiny fruit, but not belonging to Eehino- 

 cereus ; it is probable "that Pfeiffera, 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 

 areola?, while in Pilocereus the fertile areola} 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 9 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 over 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, opeu only at night; ovary angular, with 



