I LAND AKB FEESHWATER 



I am most fortunate in having as a neighbour ilr. J. S. Gladstone, 

 an excelleut and skilful photographer. Without, his valued aid 

 1 could not give the figures of tjpes and shells from typical 

 localities, which show far better than any de8cri])tion the direction 

 their subtle ditf'erences take. For instance, how distinctly jihoto- 

 grapliy shows the difference between y. lenui.^jiirn of Teria Ghat 

 (I'late CLIX. fig. 3) and the species for long regarded as the same 

 from Sikhim (I'late CLIX. figs. 1 & 2). Mr. Gladstone made 

 jihotographs of 60 shells, which fill three Plates. 1 may say here, 

 but for this generous assistance, the publication of this Jlonograph 

 would not have been possible. As an example of Zoological 

 liesearch it has been met, and by private means alone. 



Genus Glesscla. 



While I have been studying this genus, particularly the animal, 

 as specimens were slowly obtained in spirit, knowledge of its 

 taxonomy has increased. Tliis has led me to look at many species 

 very closely, for much had been left iucomjdete by Colonel Eeddome, 

 particularly the species from the North-East Frontier of India, of 

 which I possessed a very fine series. 



Some of this work on the genus Olessula might have been 

 published long ago in the second volume of the ' Fauna of British 

 India' — some of it, anatomical, had been done ready for it: 

 but I found 1 could not, under the conditions in which I was 

 expected to work, complete it in time. I had reached an age when 

 extra correspondence was to be avoided, when indejjendeiit con- 

 chological work was pleasanter to do. It was not to be expected 

 I could place m}' collection at the service of others, neither could 

 I hand over original work on the animals of the genus on which I 

 had spent so much time and expense during many years. I 

 could not give the public the run of collections I had deposited 

 in the Natural History Museum under certain well-defined and 

 very reasonable conditions, reserving to myself the right to work 

 on them during my lifetime. 



At the end of Vol. II. (p. 435) I mentioned the genera I was 

 engaged upon and trusted to deal with. Of these Glessttla has 

 been completed and is now presented in Part I. of this new 

 volume. The anatomy of several species has been made known, 

 and, when working out the collections made w hen the punitive 

 expedition entered the Abor country and the Tsanspu Valley 

 (1911-12), I took the opportunity of publishing the anatomy of 

 a new species from Sikhim to elucidate that of the genus, 

 as I did not see at the time, with the war going on, anj- chance of 

 piil)lishing it at all. The animals of other genera have come 

 to hand and have been described and figured in the following 



