14 DR. NELSON ANNANDALE ON 



and that of the mouth a trifle more than ± of its length; the height 

 of the mouth a little less than | that of the shell, and the width of 

 the mouth just less than half of that of the shell. 



Type-specimens. No. M. -— Z. S. I. (Ind. Mus.) 



This species is apparently the common one in the rice-fields 

 round Bangkok. Dr. Malcolm Smith sent me several indivi- 

 duals found active in ponds in July. They arrived in Calcutta 

 by post from Bangkok with the shell tightly closed by the oper- 

 culum. They were placed in a dish of water and after about an 

 hour the operculum gradually opened. The animal, however, remain- 

 ed very si uggish for the rest of the day and did not begin to feed 

 until next morning. When they arrived the lung was evidently 

 full of air as they floated in water. Dr. Smith tells me that the 

 eggs are conspicuous in the rice-fields in the winter months. 



I am indebted to Dr. Baini Prashad for the following parti- 

 culars of the anatomy : — 



"The animal of this species is on the whole of a much more 

 massive type than of the common P. globosa of Bengal. The fol- 

 lowing anatomical points are interesting from a comparative point of 

 view. 



" Both the cephalic and the true pair of tentacles are long, 

 when fully extended the true tentacles are at least two and a half 

 times as long as the cephalic ones. Both pairs of tentacles are 

 fairy thick at the base but taper to a point very gradually. The 

 eye-stalks are small and thick. Both the nuchal lobes are well 

 developed. The right lobe, though not forming an actual siphon as 

 in Vivipara, forms a fairy deep groove. The left, or the respiratory 

 siphon of the family, forms a comparatively broad and thick res- 

 piratory tube, slightly different in size and proportions from that of 

 P. globosa but much more so when compared with that of 

 Ampullaria insularum d'Orbigny, as figured by Fischer and 

 Bouvier. ] The margin of the mantle is very thick. The osphradium 

 is large, and owing to the large development of tissue at its base may 

 be described as pedunculate. The lung is a copious structure with a 



1 .Town, de Conchyl. XL, pi. iii, fig. 15. 



JOURN. NAT. HIST. S0C. SUM. 



