the Embryos and Seedlings of the Cadaceae . 443 
3. Genus Cereus. 
C. Thurberi , Engelm. Figure 8. 
C . gigantetis , Engelm. Figure 9. 
C. peruvianus, Mill. Figure 10. 
C. Hystrix , Sweet. Figure 11. 
C. Bonplandi, Parm. Figure 12. 
C. Martianus , Zucc. Figure 13. 
C. grandijlorus , Mill. Figure 14; also Fig. 5, PL II, Goebel, Schilderungen, I. 
C. nycticaulis , Link. Figure 15. 
C. spinulosus , DC. Figure 16. 
C. triangularis , Mill. Figure 17. 
C. subrepandus , Haw. Figure 10, PI. XVI, in Pfeiffer. 
C. eriophorus, Hort. Figures 4, 5, 6, 7, PI. II, in Zuccarini. 
C. Gregii , Engelm. Figure, PI. LXIII, in Engelmann. 
C. Emory i, Engelm. Figure, in Lubbock, II, 9. 
This genus consists of stout columnar to short almost 
globular, or else deflexed or creeping or slender climbing 
forms, rarely jointed, always (excluding Phyltocadus ) radial, 
generally ribbed. We recognize, with Schumann in his latest 
monograph, four main divisions : — A, those with erect columnar 
stems ; B, those with stems at first upright, but at length 
declined on the ground ; C, those at first upright, later leaning 
upon supports, and thus climbing or hanging but lacking 
aerial roots ; D , those climbing and possessing aerial roots. 
This apparently very artificial division is much more natural 
than it seems, but is far from satisfactory. It is, however, 
the best we have. In this family, as Schumann has pointed 
out, the vegetative characters are more important in classifica- 
tion than those taken from the flowers, which in the large 
genera are singularly uniform. 
Taking Cereus as a whole, we find throughout a succulent 
hypocotyl, with distinct cotyledons, usually broad at the base 
and set a little apart, with bases parallel. In the relatively 
large size of the cotyledons they approach Opuntia. But 
in the different divisions there are differences which are fairly 
constant and which usually distinguish them. Of the impor- 
tant columnar group, good types are C. Thurberi and giganteus 
(Figs. 8 and 9). In these two very similar and closely related 
