CHEMNITZIA. 421 
nence, a pyriform red-brown or yellowish obliquely striated 
operculum. 
There being some maccuracies in my account of the C. 
acuta in the ‘ Annals’ referred to above, I have reproduced 
it; as it is an important species embracing several others of 
doubtful parentage and some varieties, which latter produce 
the three following distinct forms. The slender subcylindrical 
variety passes in all collections for the coralline zone C. pii- 
cata; this is an error: an examination of the animal shows 
it to be a C. acuta, differing materially in its organs from 
the true “plicata,’ which is essentially a littoral animal, 
rarely, if ever, found beyond that limit: I have hundreds of 
examples taken alive. The next form is that of the common 
livid flesh or pearl-coloured glossy shell of 5-6 volutions, 
with a cone of broader basal dimensions. This is the type, and 
though usually smooth in the aperture, is sometimes furnished 
with transverse crenve in the throat. I have four which were 
examined alive in comparison with the smooth ones, and they 
are, both in shell and animal, identical; it is difficult to 
account for the occasional presence of distinct crenz in the 
same species. The third form is of the larger size of 6-8 
volutions with white shells; these are smooth, though some- 
times furnished with striz in the throat of the aperture ; 
I have several of each, which are so exactly represented by 
the figure of Mr. Alder’s O. conspicua in the ‘ British Mol- 
lusea,’ that I am induced to consider that species as a large 
crenated C. acuta; and it is not improbable that the 
O. striolata of the same author, like the C. turrita, may 
be a striated C. acuta, which are all more or less furnished 
with spiral striz on the volutions. I must observe, that the 
crenated examples of C. acuta must not be confounded with 
any variety of C. conoidea, as the animals of the two are very 
different ; and as regards the shell, the cone of the one atte- 
nuates suddenly, whilst in the C. conoidea it diminishes more 
gradually and tumidly. 
The C. acuta is by far the most abundant Chemnitzia of 
the South Devon coasts, and is taken in the coralline and 
muddy shelly districts. Independent of the three principal 
