Note on Melocactus viridescens. 293 
Nassa: ELATA. Pl. XXIV. Fig. 11. 
Testa elongato-conicá, cinereo-albidá ; anfract. 8 tabulatis, marginatis, 
posterioribus plieatis, penultimo glabro, ultimo anticé striato; apertura 
angustá, ovali, albá ; labro acuto, anticé crenulato, intus striato. 
Long. 32 ; lat. 3; poll. 
A pretty, dingy-white shell, its slender, elongated forin 
giving it somewhat the aspect of a Terebra. It is remarkable 
for its varied sculpture. There are 8 flattened, turreted 
whorls, with a marginalline near the suture. "The six upper 
ones are marked with regular, somewhat distant, acute folds; 
the last but one and the upper half of the last are smooth, and ` 
the lower half is occupied by about half a dozen regular, 
deeply impressed, revolving strie. Aperture small and nar- 
row, less than half the length of the shell; lip sharp, some- 
what sinuate near the front, and rendered serrate where the 
revolving strie cut it; striate and white within; callus on the 
columella rather sparing. 
ART. XX. — NOTE ON MELOCACTUS VIRIDESCENS, Nvrr. (ECHI- 
" NOCACTUS, Torr. & Ga.) By J. E. TEscHEMACHER 
I see to communicate to the Society that I have just re- 
ceived from San Diego, California, a living specimen of Melo- 
cactus viridescens of Nuttall, MSS. communicated to Messrs. 
Torrey and Gray, and published by them in their invaluable 
Tk on the plants of North America, as an Echinocactus. 
this difference of opinion arose probably from Nuttall’s de- 
| iption stating that the flowers proceeded from the upper 
clusters of spines, whereas the flowers of Melocactus proceed 
from the woolly head characteristic of this genus, in which 
they are usually imbedded. But Nuttall also states that the 
fruit is smooth; this is a character of Melocactus, the fruit 
of Echinocactus being generally more or less scaly from the 
s “remains of the sepals; Pfeiffer says rarissime levis. 
My specimen is about 5 inches high, and 9 inches diameter ; 
the boum are radiating, very —_ and transversely striate ; 
d 
