8 



POPULAR CONCHOLOGY. 



season, and the oyster not much less : fortunately land 

 shells are less prolific. The eggs of land genera are 

 separate, those of sea shells adhere together in masses.* 



The following interesting account of the proceedings of 

 the Paludina impura (Bithinia tentaculata Gray) is taken 

 from Forbes and Hanley's work on British Mollusca, and 

 will inform the reader of the method pursued by some of 

 these curious creatures. " The B, tentaculata lays from 

 May to August. There are usually from thirty to seventy 

 globular, yellowish, hyaline eggs, which are united together 

 in a band, and attached to stones or the stems of aquatic 

 plants. When the animal desires to lay, it seeks some 

 smooth place, and begins to clean the surface with its 

 mouth before commencing. That being done, it contracts 

 its foot, so as to render itself a third shorter than its 

 usual dimensions when creeping, but also a third broader. 

 Then ceasing to use its mouth, it raises the centre of the 

 anterior extremity of its foot, so as to form a little canal 

 intended to receive the egg. It next withdraws its head 

 a little within the shell, and directs its muzzle towards 

 the branchial orifice where an egg appears, which it seizes 

 and guides into the little canal to fix it in its destined 

 locality. Then the animal cleans the body to which it 

 adheres anew, and deposits a second egg, repeating the 

 operation, until at last all the eggs are expelled, and 

 arranged in ribbon fashion, each band, when laid by 

 an adult, consisting of three rows. The whole process 

 proceeds slowly, time being left between each effort 

 sufficient for the agglutination of the egg. The young 

 ones emerge at the end of from twenty to twenty-five 

 days, and do not attain full growth until the end of 

 their second year." 



Woodward's Recent and Fossil Shells. 



