THE ANNALS 
MAGAZINE OF NATURAL HISTORY. 
[THIRD SERIES. ] 
No. 78. JUNE 1864. 
XLI.—On the Classification of the Cyclostomacea of Eastern 
Asia. By Wivu1am T. Bianrorp, A.R.S.M., F.G.S. 
THE most generally received system of tacit for the 
various forms of operculated land-shells is, I believe, that of 
Dr. Pfeiffer, as amended in the supplement, published in 1858, 
to his invaluable work, the ‘ Monographia Pheumonopomorum 
viventium.’? The additions which have since been made to the 
genera belonging to the group in most cases fall naturally into 
the several divisions proposed. 
My own observations have been limited to the land-shells 
inhabiting India and Burma; but a close comparison of a large 
number of these, together with the examination, in many genera, 
of the animals, had induced me to believe that several slight 
alterations and one or two important changes are requisite in 
Dr. Pfeiffer’s classification, in order to bring it into accordance 
with the natural affinities of the forms included. I propose, 
therefore, in the present paper, briefly to review the various 
admitted genera and subgenera, to propose a few additions, and 
to add some remarks upon the distribution and mutual affinities 
of several of the species. 
Too much stress appears to me to have been placed upon the 
structure of the operculum. In some instances the characters 
of genera, or even of subfamilies, mainly based upon this portion 
of the animal, only apply to a minority of the species or genera 
included. So long as an examination of the animal was im- 
practicable, it was only natural that much importance should be 
attached to the structure of the operculum; and doubtless it is 
in general a valuable indication of the affinities of different 
species. But there are many cases in which its structure alone 
is insufficient to establish the relations of the animal. One re- 
markable instance may be quoted : Cyclostoma semistriatum, Sow., 
and C. filocinctum, Bens., both have a concentric, multispiral, 
Amn. & Mag. N. Hist, Ser.3. Vol. xii. 
