3 22 Shell Life 



than eight coils squeezed together. The upper-side 

 is flat, with a depression in the centre, tlie under-side 

 concave, with a wide and deep umbilicus. The mouth 

 of the shell is crescent-shaped. The animal is not 

 very active, though it is fond of floating at the 

 surface. The egg-capsules of this species only contain 

 from 6 to 8 eggs, and the total number of eggs laid 

 during the season is only about 50 per indi\idual. 

 It is widely distributed throughout the ponds and 

 ditches of Britain, and occurs in tlic counties of 

 Limerick and Tipperary, Ireland. 



The following four species resemble each other to 

 this extent, that their whorls are numerous, angular, 

 and more or less distinctly keeled. The Round-spired 

 Trumpet (P. sjni'orhis) is so named because its keel 

 is blunt and but little developed. It is little more 

 than a quarter of an inch across, very thin, one 

 surface concave, the other almost flat; the mouth 

 nearly circular. Umbilicus large and shallow. Found 

 in shallow grassy pools throughout the country. The 

 Whirlpool Trumpet-snail (P. vortex) is very similar, 

 but the shell is larger, thinner, flatter, and 

 more distinctly keeled towards the lower side. 

 The mouth, too, is more oval and angular 

 than round. It is found in similar situations 

 to the last, but is not so plentiful. The 

 Keeled Trumpet - snail (P. carinatus) is a 

 much thicker disk, and measures half an inch 

 across. The prominent keel is at or near the centre 

 of the edge. The mouth is an oblique oval, with a 

 sharp angle above. The flatness of the under-side 

 makes the umbilicus very indistinct. It is no- 

 where very plentiful, but is more frequent in the 



