LAND AND FRESHWATER MOLLUSCA 
OF 
| si et 68 bial ar 
Part ITI._ JANUARY 1883. 
(Plates XIII.-XX1.) 
Tue shells that are now figured on Plates XIII. to XVII. are all 
of very small size, and many of them are described for the first 
time. I had hoped in this Part to be able to figure some of the 
small operculated shells which are included in Mr. Sylvanus 
Hanley’s “ Systematic List of Species ” in the ‘Conchologia Indica,’ 
though not figured in that work, and the large number that have 
been found since ; but Ihave thought it best to continue the minute 
Zonitide, and record the little-known forms of this family before 
entering on another. 
It has become somewhat a difficult matter to know under what 
genus to place most of these little shells. We know nothing of the 
animals, still less of their anatomy: in the case of some species it is 
doubtful even to what family they belong; for instance, the more 
or less depressedly pyramidal shells on Plate XVI. are transversely 
sculptured like Kalella, and I bring them into that subgenus. 
In India the Zonitide altogether exceed the Helicide in number, 
and those genera and subgenera which come into the latter family 
are mostly of large and characteristic form. 
I am therefore obliged to group them, to a certain extent, by 
outward form of shell and the sculpture well magnified ; and as this 
depends almost entirely on the form and action of the mantle, it is 
of a certain value. Thus guided by sculpture, those shells figured on 
Plate XIII. approach the subgenus Sitala, for longitudinal ribbing 
is characteristic of all and is always well seen on the base and 
apex, though somewhat obliterated on the face of the whorls by the 
transverse lines of growth. In the strong epidermis of some, hirsute 
in others, or very oblique undulate ribbing there is much divergence ; 
and these again merge into forms like Mucrochlamys, as shown on 
Plate XIV., to which I suspect several belong. 
For some of these species we might establish subgeneric titles, 
and they will perhaps be necessary to complete the chain of classifi- 
cation ; it is better, however, to wait and learn more about them 
PART III. H 
