FRESHWATER GASTROPODA FROM BIADAGASCAR. 377 



In the appended details the twenty-five (out o£ thirty-two) peculiar species 

 are indicated by an asterisk. 



Note. — Since writing this introduction the author has received an in- 

 teresting conniiunication from Colonel H. H. Godwin-Austen, F.R.S., with 

 reference to the community of species between Madagascar, Mauritius, and 

 India. He draws attention to the fact that an Assamese species of Macro- 

 clilamys has been introduced into Mauritius with dhan, or unhusked rice, 

 exported from Assam, and goes on to say : " I feel quite convinced that 

 India, Madagascar, and the E. coasts of Africa have been in connection with 

 each other by native craft going back 4000 years or more. The Banana has 

 played its part in the transmission of species.'^ Such observations show that 

 caution is necessary in dealing with cases of community of species between 

 the East and West coasts of the Indian Ocean. For a more extended 

 survey of this question^ cf. Grodwin-Austen, Proc. Malac. Soc. 1908, p. 146. 

 The author has to thank Col. Godwin-Austen for valuable assistance and 

 advice in the determination of some of the forms here enumerated. 



List of Species. 



STREPTONEURA. 



1. Nbritina gagates, Lamk. 



Lamarck, An. s. Vert., 1822, p. 185. 



Betw^een Tamatave and Marodasatia (Antongil Bay), E. Madagascar. 



Representative examples. 



So far as can be discovered, this is the first notice of the species from 

 Madagascar, though it has been previously recorded from Mauritius and the 

 adjacent islands. 



2. Neritina [Olypeolum] pulligera, Lmn., var. Knorri, Recluz. 



Linne, Syst. Nat. ed. xii. p. 1253. 



Locality. Vide no. 1. 



A small discoloured example. 



This variety, according to examples in the British Museum, extends as 

 far east as the Goram Is. (New Guinea), and is also found in Continental 

 Africa. The species is also found in Australia and C. Polynesia {Pilsbry). 



3. ? Cleopatra trabonjiensis, E. A. Smith. 



E. A. Smith, P. Z. S. 1882. 



Lake Alaotra, N. end. 



Cleopatra multilirata and CI. Smithii, Ancey (Nautilus, xx. 1906, p. 45) 

 are strikingly like this species, and do not appear to differ specifically. 



