34 THE DISPERSAL OF SHELLS. 



searching for land-shells in a garden in Old Panama, 

 where, it is stated, "they had been left after the rainy 

 season,"' and the occasional occurrence of living P/i*/^/^ 

 on land, at some little distance from water, is familiar to 

 many observers. A little observation, recently recorded, 

 on the transportal of a shell by a mountain torrent is 

 perhaps worth giving. A house in which an English 

 naturalist stayed in Trinidad had a bath-room con- 

 structed so that a rapid stream (under control) flowed 

 in at one end and out at the other, and here, it is said, 

 the bather was joined sometimes by a specimen or two 

 of the "ram's-horn water-snail," which "would occa- 

 sionally come toppling down the rushing waters to a 

 deeper and quieter portion of the channel below." ^ 



Shells adhering to detached and floating water-plants 

 seem eminently liable to transmission by rivers, and 

 when swept away during floods may be carried occa- 

 sionally to ponds or other waters at a considerable 

 distance from the river-bed. It is interesting to note that 

 a handful of dead pond-weed {Potai/iogeton)^ which was 

 floating in a ditch and might have been carried to a 

 great distance in some circumstances, was once found 

 by Mr. W. K. Bridgman to contain " about a table- 

 spoonful" of little nautilus coil-shells [Planorbis im- 

 bricatus) ! -^ Live shells, it is well known, are frequently 



^ Reeve, '• Land and Fresh-water Mollusks,'" 1863, p. 236. 



2 H. H. Higgins, "Address to Liverpool Naturalists' Field Club," 

 Jan. 30, 1891, p. I']. 



3 = Planorbis ?iautileus ; W. K. Bridgman, " Zoologist," ix. 

 (1851), 3302. 



