15 



douce," published in the Xouvelles Archives du Museum d'Histoire Naturelle, 

 series 4, Vols. VI. -VIII., 1904-1906. 



Though I do not accept Miss Rathbun's synthesis of subgenera and genera, 

 I must express my admiration of her analytical tables of species, — the con- 

 struction of which must have involved a prodigious amount of research and 

 labour ; and I must particularly admit the assistance that I have derived from 

 her monumental bibliography of the Family. The existence of this bibliography 

 relieves me of the responsibility of attempting anything of the sort for the 

 Indian Potamonidoe, and provides a canonical reference for the several species 

 described in the sequel. 



I have elsewhere expressed my acknowledgments of the friendly help 

 that I have so often received from Dr W. T. Caiman of the British Museum ; 

 and I must also mention my obhgation to Professor E. L. Bouvier, the 

 renowned successor of renowned predecessors at Paris, for his kindness in 

 authenticating one of my specimens that could not be resolved without an 

 actual comparison with a type. 



Finally, my thanks are due to the library staff, both of the British Museum 

 in Cromwell Koad and of the Zoological Society in Hanover Square, for the 

 ready way in which they have often helped me, and to Dr Annandale for his 

 liberal treatment of all my requirements. 



The new species described in the following pages have already been briefly 

 characterized in "Records of the Indian Museum," Vol. III., Parts III. and 

 IV., for 1909. 



