CACTACEH OF THE BOUNDARY. 217 
a mistake; but the sheath is probably not as loose asin others. It corresponds, therefore, with my var. brevispina, Synops. Cact. 
in Proe. Amer. Acad. Arts and Sci., Vol. III. In delicate specimens — and such are usually the cultivated ones — the spines of 
most of the cylindric Opwntie do not exhibit the sheath very plainly ; it ¥ senally adheres closely to the body of the spine. 
This vagina consists, like the whole spine, of elongated indurated cells; the barbs of the spine are covered by it and are 
closely adpressed until the vagina detaches itself, which commonly takes aes very early. 
Mr. Paulus Reetter, of St. Louis, made the drawings for the plates under the close superintendence of the author, 
The steel engravings were done partly by Mr. W. H. Dougal, of Georgetown, D. C.; a few by Messrs, Maillard & Connor, 
of St. is; and the balance by European artists, namely, — Mr. Weber, of Berlin, Prussia, and Mr. Davesne, [78] 
Mr. Rebuffet, Mr. Martin Schmelz, and the brothers Picart, all of Paris, France. The high order of iM of the 
engravings, especially of those of the Picarts and of Schmelz, cannot fail to strike those who examine the 
gures of the embryos in Plates XXIV., XXXIV., XLI., and XLVII., the line indicating a division of the 
cotyledons does not show in all the copies. The embryo in Plates XXIV. and XXXIV. resembles that of Plate LXXIV. 
figs. 9 and 10 ; and that of Plates XLI. and XLVIL, is like that on Plate LV. 
St, Louis, November, 1858. 
EXPLANATION OF PLATES. 
Remarks. — All the figures are in natural size unless otherwise stated. The seeds of Mamillarie, Echinocacti, and [63] 
Cerei are represented in the natural size, and eight times magnified: a@ is a lateral view, natural size ; b, same, eight times 
magnified ; ¢, part of the surface of the seed still more magnified ; @, seed after the removal of the outer coat, with endopleura 
and albumen ; ¢, embryo; /, another form of same seed; g, ‘iacdting plant ; 4, back view; 7, front view; %, basal view; 
1, top view of embryo. All eight times magnifie 
Th ds of Opuntie, being larger, are reginnenited a, side view, natural size; 6, same, four times magnified, as 
are all the following ones; ¢, posterior view; d, anterior view; e, vertical section; f, seed after the removal of the testa; 
g, embryo. 
The landscape opposite the titlepage represents a region near the Colorado River, with several Cacti, especially Cereus 
giganteus ; one of them decayed, showing the form of the ligneous skeleton. The different plants are accurate copies of 
nature. 
Plate I. MAMILLARIA MICROMERIS: 1, a young plant not yet blooming, without the tuft; 2, a plant in bloom, with 
the tuft; 3 and 4, different views of a plant of the largest size, — several fruits are seen in the tuft ; 5, a tubercle with a bunch 
of oe eight times magnified ; 6, a bunch of spines in natural size, and 7, the same, eight times enlarged. 
e II. teral view of a bunch of spines, and its wool on the flower-bearing part of the plant, ~~ 
times sand, ce oteqedan = “eee elongated clavate spines; 2, flower, four times enlarged ; 3, fruit ; 4, seed. — Fi 
M. MICROMERIS, var. GRE : 5, bunch of spines; 6, same, eight times magnified, showing the ragged ends of eis oo 
spines where they are Saray off ; 7, a bunch of spines, with its wool from the flowering part of the aaa with the long clavate 
spines, eight times magnified ; 8, seed. 
Plate III. M. LastacanrHa: 1, a plant of the ordinary size in flower; 2, flower, four times magnified ; 8, a tubercle 
with a bunch of spines, showing the pubescence, eight times magnified ; 4-5, bunches of spines, natural size, and eight times 
magnified. 
Plate IV. M. LASIACANTHA, var. DENUDATA: 1, a fruit-bearing plant ; 2, a tubercle, with its bunch of spines, eight 
times magnified ; 3-4, bunches of spines in natural size, and the same eight times magnified ; 
Plate V. M. pusiiLa, var. Texana: 1, whole plant in flower; 2, a ers with a bunch of spines and the axillary 
wool, twice magnified ; 3, a bunch of spines, same; 4, flower, same; 5, fruit natural size; 6, seed. 
Plate VI., fig. 1-8. M. Granamr: 1, asingle plant; 2-4, bunches = spines, with one, two, and three oes [64] 
spines; 5, a tubercle mad rn of spines, magnified twice; 6, a bunch of spines from Dr. Parry’s specimen 
Colorado, eth magnified t ; 7, a flower from A. Schott’s specimen from the Gila; 8, seed. — Fig. 9-12. < BARBATA : 
9, a tubercle and bunch re ime natural size; 10, bunch of spines, magnified twice; 11, fruit; 12, seed. 
Plate VII. M. PHELLOsPERMA: 1, a flowerless plant ; 2, a bunch of spines ; ; 3, a tubercle with the axillary wool and 
gg and the terminal bunch of spines, twice magnified ; 4-6, bunches of spines, with one or more hooks, twice the natural 
sau fruits of different size; 9, seed. 
e VIII, fig. 1-8. M. Wrientir: 1, a whole plant in fruit, from a sketch of Mr. Moellhausen’s ; 2, a young, and, 
3, an ie hase with spines, of the same specimen ; 4~6, spines of a specimen from the Copper-mines, four from the older 
part of the plant; 7, flower; 8, seed. — Fig. 9-14. M. Goopriperr: 9, tubercle with spines ; 10, bunch of spines, natural 
size ; 11-12, tubercles with the axillary wool and bristles, and the spines ; 13-14, bunches of spines. The last four figures are 
inagnified twice, 
Plate IX., fig. 1-3. M. MEIAcANTHA: 1, whole plant in flower; 2, fruit; 3, seed. — Fig, 4-14. M. Heryprrt, var. 
28 
