CACTACESR. 15 
larly shrivelled up as in those species, but forming a regular, conic, whitish head on the red 
fruit. Seeds 0.4 or 0.6 line long, unusually thick, with a very small oval, not linear, hilum. 
20. M. pasYAcANTHA (sp. nov.): simplex, subglobosa; tuberculis teretibus leviter usque ad 
basin sulcatis laxis ; axillis suleoque subvillosis mox nudatis ; areolis orbiculatis novellis, albo- 
tomentosis ; aculeis gracilibus vix spinescentibus rectis patulis, exterioribus 25-35 capillaceis 
albidis apice sphacelatis, interioribus 7-13 setaceis longioribus infra pallidioribus sursum pur- 
pureo-fuscis apice atratis, centrali singulo equilongo porrecto nune deficiente; florum parvorum 
centralium sepalis arachnoideo-fimbriatis ; baccis verticalibus ovatis parvis ; seminibus obovato- 
globosis angulatis scrobiculatis nigricantibus ; hilo lineari subventrali. (Tab, XII, fig. 17-18.) 
El Paso and Eagle springs, Wright.—The few specimens before me are from 1}-23 inches 
high, alittle less in diameter ; tubercles slender, 4-5 lines long, in 13 spiral rows; grooves 
slightly hairy when young; axils more or less villous, soon becoming naked. Spines not strictly 
radiating, but loosely spreading, much more slender than in the last and the next species, often 
even capillary ; exterior ones 3-6 or even 9 lines long; interior spines forming a circle corre- 
sponding with the interior ones, but darker, stiffer, and longer, upper ones 8-12 lines, lower 
ones 6-9 lines long, or in some specimens shorter and slenderer ; central spine single, erect, 
6-10 lines long, often wanting. The dry and shrivelled fruit, found on the tomentose vertex, 
was only 34 lines long; seeds thick, sometimes triangular, with a very broad back, 0.4—0.6 
line long, almost black; hilum quite different in shape and position from that of the next 
species, to which this is closely allied. The plant so much resembles Echinocactus intertextus 
var. dasyacanthus that, at first sight, it might be taken for it. 
21. M. vivreara, Haw. (Cactus viviparus Nutt. Gen.) This species is found only on the 
northwestern plains, along the Upper Missouri and Yellowstone rivers, and up into the Black 
Hills and Rocky Mountains. It is a low plant, either simple or usually profusely proliferous 
and cespitose, shoots always from the base of the groove on the tubercle, or the axil proper, 
while in M. calcarata they come from the upper part of the groove, just below the spines, 
Radial spines 12-20, stiff, white, often brown-red at the top, 3-4 lines long ; central spines 
4, (3 pointing upwards, and the stoutest and shortest downwards,) but sometimes less, and 
often more, as many even as 8, usually 4—6 lines long; flowers central, large for the size of 
the plant, about 14 inch long, and even more in diameter when fully open, (which is after one 
o’clock, later than in most other Cactaceze,) with thirty or more delicately fimbriate recurved 
sepals and 25—40 narrow acuminate purple petals, which are naked or fimbriate at base ; fila- 
ments whitish or purplish, almost from the base of the tube ; anthers orange; style long-exserted 
with 5-10 linear pale or purple stigmata, which are pointed with a short mucro. Berries 
becoming lateral, being pushed aside by the continuous growth from the apex of the plant, 
oval, 4-} inch long, pale green, juicy, and slightly acid, full of yellowish-brown seeds. These 
are 0.7—-0.8 line long, obliquely obovate, somewhat concave on the compressed ventral portion 
about the small oblong-linear hilum, pitted ; albumen more distinct than in most other Mamil- 
larie; embryo straight, linear-oblong, with very short connate cotyledons. (Tab. LXIV, fig. 3.) 
The following form, from Texas, which formerly I thought I could distinguish from this 
northern species, seems to be connected to it by numerous intermediate forms, found in the geo- 
graphically intermediate region of New Mexico : 
Subspec. 8. RADIOSA: ovata seu demum subcylindrica, simplex seu e basi ramosa ; tuberculis 
teretibus laxis leviter sulcatis ; aculeis radialibus numero maxime variis (12-40), superioribus 
