EXPLANATIONS OF THE PLATES OF CACTACEA. 
Pu, I. Ecutnocactus Wutrriet, E. & B.: fig. 1, whole plant; fig. 2, bunch of spines of the 
usual size; fig. 3, same, uncommonly large and broad ; fig. 4, same, lateral view ; fig. 5, same, 
very young; fig. 6, seed—qa natural size, b magnified 8 dintnekars. e part of the surface still 
more magnified to exhibit the tuberculated appearance. 
Pu. Il, Fig. 1-2. Ecurnocactus potyanorstrus, EK. & B.: 1, upper part of a rib with older 
and younger bunches of spines, the youngest one with a flower bud in the axil; 2, one of the 
largest and most fully developed bunches of spines. 
Fie. 3-5. Ecutnocactus Le Contest, E.: 3, part of a rib, with 2 bunches of spines ; 4, a single 
bunch of spines from another specimen ; 5, seed—a natural size, b magnified 8 diameters, c part 
of the surface still more magnified to exhibit the oval pits. 
Pu, II, Fig. 1-2. Ecumocacrus Wistizeyt, E.: 1, side view of a bunch of spines ; 2, seed—a 
natural size, b magnified 8 diameters, c part of the surface still more magnified to exhibit the 
reticulation. This species, collected by Captain Whipple on the Gila, and common about El 
Paso, on the Rio Grande, has been introduced here to show those characteristics which distin- 
guish it from the nearly allied LZ. Le Contei, on the foregoing plate. 
Fie. 3. Ecutnocactus Emoryi, E.: two bunches of spines on part of a rib. 
Fie. 4-6. Ecurnocacrus potycepHatus, E. & B.: 4, part of a rib, with 3 bunches of short, 
stout, and straightish spines; 5, a young bunch of spines of memes dimensions and sang 
od, with a woolly fruit in the axil ; 6, seed—a natural size, b magnified 8 diameters, c part 
of the ‘a more magnified to shoe en warty appearance, d seed after the removal of the 
outer integument, embryo, together with a considerable quantity of albumen in the endopleura, 
e embryo curved with accumbent cotyledons. 
Pi. IV, Fig. 1-3. Cereus pua@niceus, E.: 1, upper part of a head bearing a flower; 2, a 
bunch of spines of the usual size ; 3, part of arib, with 3 bunches of spines from an uncommonly 
large form. 
Fie. 4-5. CEREus PHENICEUS, suby sp. conorpEus, E. & B.: 4, upper part of a head ; 5, part of 
a . with 2 bunches of spines. 
6-7. CeREUs TRIGLocHIDIATUS, E.: 6, upper part of a large head, with a flower; 7, part 
of a ok of another specimen, with smaller curved spines. 
Fie. 8. Cereus Mosavensis, E. & B.: part of a rib, with 3 bunches of spines. 
Fie. 9. Cereus Mosavensis, E. & B., var. zunrensis: part of a rib, with 2 bunches of spines. 
Pu. V, Fig. 1. Cereus emfitsevs, E E. & B.: upper part of a head. 
Fig. 2-3. Cereus conacantuus, E, & B.: 2, part of a rib, with two bunches of spines; 3, 
another fascicle of spines ; the 3 bunches of spines show all a different proportion of the central 
and the upper radial spines. 
Fie. 4—7. Cereus ENGELMANNI, var. VARIEGATUS, E. & B,: 4 and 5, two bunches of spines, 
showing a different arrangement of central spines ; 6, fruit ; 7, edo natural size, 6 magnified 
8 diameters, ¢ part of the surface still more ringnihed to show the irregular tuberculation. 
Fig. 8-10. Cereus ENGELMANNI, var. cHRYSocENTRUS, E. & B.: 8, part of two ribs, with 
numerous spines ; 9, a single bunch of spines ; 10, fruit, sterile and perhaps not fully developed. 
Pi. VI, Fig. 1-3. Opuntia cuLorotica, E, & B.: 1, joint with a flower. The flower i= 
reconstructed from a withered specimen collected in January; 2, sterile and probably unde- 
