454 Ganong . — The Comparative Morphology of 
cotyledons, in which one can imagine a resemblance to those 
of R. Cassytha , and which also recall Cereus. The remarkable 
figure given by Pfeiffer I do not understand, and think it must 
represent something abnormal, for the epicotyl as he figures 
it is like nothing I have seen in this family. Probably the 
embryos and seedlings would show whether this genus belongs 
more nearly with Rhipsalis or with Cereus. Vochting, 
reasoning from anatomy, considered that Pfeiffera is the 
nearest living representative of the connecting forms between 
Cereus and Rhipsalis. 
13. Genus Echinocactus. 
E. robustus, Otto. Figure 6 in Pfeiffer, PI. XVI. 
E. Wislizeni, Engelm. Figure 32. 
E. viridescens, Nutt. Figure 33 ; also in Lubbock, II, p. 8. 
E. texensis, Hopf. Figure 34. 
E. cornigerus , DC. Figure 36; also in De Candolle (Memoire), PI. X, 
Figs. 5-7. 
E. longihamatus , Gal. Figure 35. 
E. setispinus , Engelm. and Gray. Figure in Maxwell, p. 29. 
E. recurvus, Link and Otto. Figure in Pfeiffer (as E. spiralis ), PI. XVI, Fig. 7. 
E. ingens , Zucc. Figure 37; also in Pfeiffer, PI. XVI, Fig. 5; also in Goebel 
(as E. aulacoganus ), p. 86. 
E. horizontalonius , Lem. Figure 38. 
E. phyllacanthus, Mart. Figure in Zuccarini, PI. II, Fig. 3 (seedling). 
E. Williamsii, Lem. Figure 39. 
E. myriostigma, Salm-Dyck. Figure 40. 
E. capricornis , A. Dietr. Figure 41. 
E. lophothele, Salm-Dyck. Figure 42. 
E. Scheerii , Salm-Dyck. Figure 43. 
E. Simsoni , Engelm. Figure in Engelmann, Simson’s Expedition, PI. II, Fig. 16. 
E. corynodes , Otto. Figure in Zuccarini, PL I, Fig. Ill, 3, 4 ; also PI. II, 2, 
This very large genus contains condensed globular (be- 
coming very short cylindrical), strongly ribbed forms, with 
the ribs rarely broken to tubercles, giving a transition to 
M amillaria^ and all of true desert habitat. They doubtless 
have come off from the columnar Cerei low down on the 
stem, and near Echinopsis. 
Of the various sub-genera, some of which have been con- 
sidered in the past as distinct, the one which comes nearest 
to the Cerei is, no doubt, Schumann’s Euechinocaclus. In 
