92 VARIETIES OBTAINED AT ONE LOCALITY. 
dark brown, costate variety, with two pale lines on the thick brown 
callous of the columella. The last, although not the least interesting 
form, is an almost white shell, tessellated with brown, the strongly 
curved ribs and transverse strie showing a close connection with 
the N. marginulata, Lam., and all contained in a common half- 
penny match-box. 
There were among them two specimens so remarkably like the 
N. zonalis, A. Ad., that it is very difficult to determine in what 
respect (with the exception of size) they differ, the ground-colour, 
the banding and the general outline form of the shell and rounding 
of the whorls are all similar in each. 
SU AEM ALR 
I po not wish to state that the evidence derived from a study of 
the Nass is sufficient to prove that the genus is constituted by 
one shell in an endless variety of forms. Nevertheless, the mass 
of evidence appears to me to point in that direction. 
It is often a matter of extreme difficulty to decide whether a 
shell figured as distinct is not merely a deformity ; such abnormal 
examples may be found in the N. sulcifera, A. Ad., from Algoa Bay, 
the N. distorta, A. Ad., and the N. stolida, A. Ad., all figured 
from solitary specimens. Many of the shells in my cabinet are 
more or less deformed varieties; two of them are quite as much 
deserving of being distinguished as any of those above enume- 
rated. The first is N. picta, D’k’r., with the spire elongated 
in about the same proportion with that of the N. monile, Kien., 
variety distorta, A. Ad., and presenting as much difference from the 
ordinary state of the shell as that does. The other is N. coronata, 
Brug., with the thickened callus projecting and covering one-half 
the penult-whorl; the new piece of shelly matter forming the lip 
has been placed obliquely and has obliterated both the sutural 
canal and the nodules; a second piece is costate for about one 
quarter-of-an-inch ; this is also a former injury, and then the shell 
assumes its ordinary appearance. I should as soon think of making 
