THE ANNALS AND MAGAZINE OF NATURAL HISTORY. [THIRD SERIES.] No. 78. JUNE 1864. XLII. — On the Classification of the Cyclostomacea of Eastern Asia. By William T. Blanford, A.R.S.M., F.G.S. The most generally received system of classification 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 Pneumonopomorum 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, has 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 papei', 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 : Cyclo^toma semistriatum, Sow., and C. filocinctum, Bens., both have a concentric, multispiral, Ann. i^ Mag. N. Hist. Ser. 3. Vol.xm. 29
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