part of the last whorl has become detached, and the tube, 

 which is quite free, is directed towards the penultimate 

 whorl. 



As regards the circulatory system, the Indian land 

 operculates are provided with only one auricle, and the 

 pulmonary veins, as w^ell as the auricle — into which they 

 open, — are situated in front of the ventricle. 



In their nervous system these families, like other Strepto- 

 neura, are characterized by the loop formed by the two 

 visceral nerve cords being twisted over itself in the form of 

 the figure 00 . They also differ widely from the Pulmonata 

 in their digestive and other organs. 



In the preparation of this volume the writer has had the 

 advantage of the co-operation of Mr. Hugh Watson, who has 

 kindly read through all the proofs, in the course of which he 

 has made many valuable suggestions. To Mr. G. 0. Robson, 

 as on a former occasion, I am indebted for giving me free 

 access to the general collection in the British Museum at 

 South Kensington. Mr. G. C. Leman also has obligingly 

 placed several specimens from the late Col. Beddome's 

 collection — now in his possession — at my disposal, while to 

 Dr. F. Haas, of the Senckenbergisches Museum, Frankfurt 

 a/M., I am under obligation for procuring me photographs 

 of the t3^[)es of two species in the Mollendorfi' Collection. 



London, Febniary, 1921. G. K. GUDE. 



