the Embryos and Seedlings of the Cactaceae. 439 
the later leaves, and probably like them they are shed at the 
dry season. The plumule shows first a leaf like the later 
ones, then another, and so on alternately. As the cotyledons 
lie in the seed they are flat, and hence very different from 
those of P. Bleo as figured by Schumann. There is no doubt 
of the identity of my seeds, for one of them grew into a 
seedling of this species. P. Pititache , as figured by Zuccarini, 
has an embryo resembling more nearly Opuntia , though the 
adult is described as woody. Probably the embryos of some 
of the succulent species, as P. spathulata , will be much like 
those of Opuntia. This mesophytic type of germinated 
embryo in P. aculeata is of course correlated with its growth 
under mesophytic conditions. No spines are produced in the 
young seedling, though the axillary buds produce the multi- 
cellular hair-like structures which are probably homologous 
with them. 
2. Genus Opuntia. 
0 . bernardina , Engelm. Figure 2. 
0 . echinocarpa, Engelm. and Bigel. Figure 3. Also in Engelmann, PL XXIV. 
O. Whipplei , Engelm. and Bigel. Figures 9, 10, PI. XXIV, in Engelmann. 
0 . vulgaris , Mill. Figure 5. Also Fig. 57 G in Schumann (Engler and Prantl). 
Also Ganong in Botanical Gazette, XXV, PI. XVI. 
0 . Rafinesquii , Engelm. Figure 7, PI. XXIII, in Engelmann. 
0 . missouriensis, DC. Figure 17, PI. XXIII, in Engelmann. 
O. tortispina , Engelm. and Bigel. Figure 5, PI. XXIII, in Engelmann. 
O. basilaris, Engelm. and Bigel. Figure 398 in Lubbock, II, 11. 
0 . basilaris ramosa. Figure 4. 
0 . E 7 igelmanni occidentalism Salm-Dyck. Figure 7. Figure 400 in Lubbock, 
II, 12. 
0 . Ficus-indica , Mill. Figure 6. Also in Schacht, Lehrbuch der Anat. u. Phys. 
der Pflanzen, Fig. 472, PI. II (not seen). 
0 . sp. ? Figure in Zuccarini, 8, PI. II. 
Very numerous beautiful figures of ungerminated embryos 
of species of Opuntia are given in Engelmann’s works. 
This genus, nearly related to Pereskia , consists of shrubby, 
branching, jointed forms, falling into two groups : — the Cylin- 
dropuntiae, living in dry deserts, with cylindrical joints and 
usually subulate leaves which may be up to an inch in 
length ; and the Platopuntiae, with flattened joints becoming 
true phyllocladia, smaller leaves, and as a rule occupying less 
H h 
