Two new genera of Cactaceae 
N. L. Britton AND J. N. Rose 
In our recent study of the genus Echinocactus, we have 
segregated a number of new genera, and restored several previ- 
iously published, among which are Malacocarpus, Gymnocalycium, 
and Discocacius, all composed of species native to South America. 
Among the North American segregates are the two described 
below, which do not belong even to the same subtribe as Echi- 
nocactus. 
, THELOCACTUS (Schumann) 
Echinocactus subgenus Thelocactus Schumann, Gesamtb. 
Kakteen 429. 1808. 
Cacti of medium size, one-jointed, solitary or caespitose, 
globose or somewhat depressed, spiny, often densely so; ribs 
few, low or even indistinct, often spiraled, divided into large 
tubercles, the flowering ones more or less grooved above; flowers 
from near the center of the plant, borne on very young tubercles, 
rather large for the subtribe, campanulate, diurnal; scales on 
the ovary usually few, their axils naked; fruit, so far as known, 
dry, dehiscing by a basal pore; seeds numerous, black, finely 
tuberculate, with a large basal hilum. 
Type species: Echinocactus hexaedrophorus Lemaire. 
The generic name refers to the tubercled ribs. 
1“ Thelocactus hexaedrophorus (Lemaire) comb. nov. 
Echinocactus hexaedrophorus Lemaire, Cact. Gen. Nov. Sp. 
27. 1839. 
2.‘ Thelocactus bicolor (Galeotti) comb. nov. 
Echinocactus bicolor Galeotti in Pfeiffer, Abbild. Beschr. Cact. 
a: ht. 25. 4648 
3 ‘Thelocactus lophothele (Salm-Dyck) comb. nov. 
Echinocactus lophothele Salm-Dyck, Allg. Gartenz. 18: 395. 
1850. 
’ NEOLLOYDIA gen. nov. | 
all, more or less caespitose plants, fibrous-rooted, cylindric, 
one-jointed, densely spiny, tubercled; tubercles borne on spiraled 
ribs, grooved above; radial spines numerous, widely spreading ; 
251 
