378 
sists of a hemispherical mass 15 cm, or more in diameter, with brain-like convolutions 
formed by the winding of a single ridge, bearing no resemblance to the normal 
plant. It is usually proliferous about the border, and I have seen develop from it 
the normal forms. There are also all intermediate forms between this and the type 
form. There occurs also a cone-like form of this monstrosity 10 to 11 em. high, 
found in the same region, but apparently developed from regular simpsoni. IT have 
seen, also, the same “brain” form assumed by Cactus niveus aristatus in speci- 
mens cultivated in Mo, Bot. Gard. It is very probable that this curious habit is far 
more general among Cacti and dchinocacti than shown by this record. 
HNCHINOCACTUS CALIFORNICUS Monville, Cat. (1846), was described 
from seedlings whose identity and native country are so very uncertain 
that no further statement can be made concerning them. 
ARTIFICIAL KEY TO THE SPECIES. 
The following key, based upon spine characters, nay be useful in case 
of incomplete material. Forms found within the boundaries of the 
United States are printed in italics. The species and varieties are 
indicated only by their specific or varietal names, and the numbers refer 
to the serial numbers of the synoptical presentation. 
* Some of the spines hooked. 
+ Central spines none. 
pubispinus (29), 
++ Central spine solitary, 
Spines annulate. 
emoryi (11). 
Spines not annulate, 
Some radials and the central hooked. 
wrightit (23), pubispinus (29), 
Only the central hooked. 
muhlenpfordtii (32). 
+++ Central spines 4. 
++ Some or all of the spines annulate. 
Radials 8 to 11. 
All the spines annulate. 
peninsule (10), 
Only the centrals annulate. 
longihamatus (20), brevispinus (21). 
Radials 12 to 14. 
eylindraceus (9), hamatocanthus (19). 
Radials 18 to 28, 
wislizent (14). 
++ ++ None of the spines annulate. 
Radials 7 or &. 
Only a central hooked. 
whipplei (25). 
Some radials and a central hooked. 
uncinatus (22), sinuatus (30). 
Radials 9 to 11, 
spinosior (26), scheerii (28), sinuatus (30). 
Radials 12 to 18. 
brevihamatus (27), scheerii (28), sinuatus (80), 
