LAND AND FRESHWATER GASTROPODA FROM MADAGASCAR. 375 



On a Collection of La-nd and Fresliwater Gastropoda from Madagascar, 

 with Descriptions of new Genera and new Species. By Guy C. Robson, 

 B.A. (Comimniicated by Prof. G. C. Bourne, F.R.S., Sec.L.S.) , . • 



(Plate 35, and 6 Text-figures.) 



(Published hy periuission of the Trustees of the British Museum.) 



[Read 4th June, 1914.] 



The collection described here was formed by the Hon. P. A. Methuen and 

 M. Perrier de la Bathie in Madagascar, and was sent by the first named to 

 Prof. G. C. Bourne, F.R.S., by whom they were handed over to the British 

 Museum for examination. The bulk of the material was collected by 

 Messrs. Methuen and de la Bathie personally during their residence in the 

 island, while a part was obtained from a field-collector^ M. Herschell Chauvin 

 Messrs. Methuen and de la Bathie have kindly presented the types of new 

 forms here described and the major part of the rest of the collection to the 

 British Museum. 



The specimens collected are mainly of conchological interest, and the new 

 genera and new species have been established upon conchological characters ; 

 but it is believed that they are sufficiently clearly marked in each case to 

 warrant such a superficial diagnosis. Examples of some of the animals of 

 which the shells have been described here are available, and it is hoped that 

 it will be possible to publish an account of the anatomy. (See Appendix.) 

 Absence of this sort of information must necessarily prevent any positive 

 assertions being made upon the relationships of the molluscan fauna of 

 Madagascar in the light of this collection, conchological resemblances being 

 very inadequate evidence for basing such generalizations upon. Certain of 

 the conclusions, provisional in so far as they depend upon conchological 

 evidence alone, may be however alluded to here. 



It has long been known that the land and freshwater Mollusca of Mada- 

 gascar exhibit closer affinities with those of the Oriental region than with 

 those of continental Africa. The resemblance may not be very marked. 

 The molluscan fauna of this island is peculiar and individual. But where its 

 affinities are obvious they appear to be as indicated above. Moreover, the 

 converse is true — some very distinctive groups of African mollusca are either 

 absent or only sparsely represented in Madagascar (Cooke, ' The Concho- 

 logist,' vol. ii.). Specimens obtained by Messrs. Methuen and de la Bathie 

 lend support to this view, though only, as has been admitted above, of a 

 provisional nature. It may be worth while to point out the interesting 

 forms. 



The new genus, for which the name Bathia has been proposed, is un- 

 doubtedly the most interesting feature of the collection. In the absence of 



