418 Original Articles. | July, 
to 6d has escaped this malformation, to a great extent, but still it is 
not always quite free from distortion. 
But the most remarkable shell “ cheated of feature by dissembling 
nature ” is shown in Figs. 3a and 3b; it is turned the wrong way, 
and this circumstance, with its peculiar ornament, gives it such a 
singular appearance, that out of twenty shells spread out on a table, 
a conchologist would certainly take up this one first, as I have verified 
by experiment. It seems to defy determination. There are two 
specimens in Captain Spratt’s collection, so that its reversal is not 
accidental, but, with its thickness and coarse ornament, is apparently 
due to its having lived under unfavourable circumstances. The 
species is certainly new, and I have called it Melania(?) anomala, 
though I am by no means sure of its genus. 
These monstrous kinds of growth are interesting on many grounds, 
and especially so in relation to the mode of formation of the deposit 
in which they oceur. Professor Forbes and Captain Spratt described 
such malformed shells from Cos several years ago in the ‘Travels in 
Lycia;’ but some of them belonged to the genus Paludina, and others, 
as in this case, to the genera Neritina and Melanopsis. The Cretan 
specimens that exhibit abnormal characters belong to the two last- 
named genera, and to the bivalve genus Unio; but the Cerithia, which 
cannot live in fresh water, are quite normal in appearance. 
Malformation as a Test of Habitat.—It is easy to see that mal- 
formations of this kind may furnish an important clue to the origin of 
a formation ; for instance, in this case, the most truly marine genus 
is represented by species exhibiting normal characters, while the more 
fresh-water genera are distorted ; thus it appears impossible to assign 
a purely fresh-water origin to the deposit, and we shall presently see 
that this conclusion is borne out by independent arguments. 
Nearly fifty years ago, M. Beudant proved by experiment, that of 
the mollusks which inhabit fresh water, those only which had the power 
of shutting off all communication between themselves and the water 
they lived in could resist the action of brackish or salt water; that is 
to say, only bivalves and operculated univalves could exist at all under 
such circumstances. Upon @ priori grounds it is allowable to extend 
this law, for certain pulmoniferous gasteropods are operculated ; but, 
as they cannot breathe without rising to the surface, and as that pro- 
cess entails repeated contact with the noxiously salt water, it is but 
reasonable to conclude that they could not long survive such a 
disagreeable necessity. We may therefore say that all pulmoniferous 
gasteropods and all non-operculated fresh-water gasteropods are unable 
to live in salt or brackish water. 
But although these bivalve and operculated univalve mollusks 
could resist the action of salt water for a time, M. Beudant found that 
even the latter could only live permanently if the water contained 
not more than 4 per cent. of saline matter, and that even this small 
quantity was sufficient to kill the bivalves after a short time ; hence 
arises the paucity of shells of the genera Unio, Cyclas, &c., in brackish 
water deposits. 
It will now be possible to discuss fairly the probability of the 
