10 
'ill 
m a 
A-/. to 
long, and an inch distant from one another; spines 9- 15 lines long. 
Flowers 2 inches long, characterized by a very slender, constricted 
tube, very different from the wide tube of the foregoing species^ Seeds 
fully 1J lines long, larger than those of any other Mamillaria examined 
by me : embryo with some albumen, curved; cotyledons foliaceous ! 
approaching the structure of the seed of most Echinocacti. 
18. M. recttrvispina, E. in B. C. R.: simplex, depresso-globosa ; 
tuberculis ovatis profunde sulcatis confertis ; areolis obliquis ovatis, 
aculeis radialibus 12 - 20 rigidis recurvis intertextis albidis corneisve, 
aculeo centrali singulo (raro binis) robustiore longiore decurvato ; 
floribus flavicantibus extus fuscatis ex axillis junioribus villosissimis. 
Sonora: fl. July. Single heads 3-8 inches in diameter; tuber¬ 
cles 5-6 lines long ; spines 4 - 9 lines long, upper ones often a little 
longer than the lower ones ; central spine 6-10 lines long, darker. 
Flowers 1J inches long. — This plant bears the closest resemblance 
to the next species, and must perhaps be classed with it; but in the 
dry specimen before me the flowers are not exactly vertical, as in that 
# * Densiflora. (Flowers and fruit remain central in the very 
woolly vertex of the plant, no new tubercles being developed be¬ 
fore the fruit falls off; berries Of all the species known to me oval, 
green ; seeds brown, smooth.) v 
19. M. coMpacta, E. in Wish Rep. : simplex, depresso-globosa; 
tuberculis abbreviato-conicis sulcatis confertis ; areolis ovato-lanceo- 
latis, aculeis radialibus 13-16 rigidis recurvis intertextis albidis cor¬ 
neisve, aculeo centrali erecto plerumque deficiente; floribus flavis 
extus fuscatis minoribus. 
Cosiquiriachi, west of Chihuahua : fl. June and July. Plant 2-4 
inches in diameter ; distinguished from the last species by the acutish 
(not obtuse) tubercles, the more elongated areola, the erect central 
spine, which however is wanting in most specimens, and principally 
by the smaller and truly vertical flowers. Spines 5-10 lines long ; 
flower 1£- 1J- inches long and wide; seed 0.7 line long. 
20. M. pectinata, E. in B. C. R.: simplex, globosa; tuberculis 
conicis abbreviatis, summis floriferis teretibus longioribus sulcatis ; are¬ 
olis oblongis ; aculeis 16 - 24 rigidis recurvis intertextis subsequalibus 
s. in tuberculis summis superioribus longioribus fasciculatis omnibus 
radiantibus corneis s. albidis ; floribus magnis sulphureis. 
On the Pecos River, in Western Texas: fl. July. — Plant 1-2 
