95 



The exact number of eggs placed in the capsules also 

 seems to have been overlooked by most workers. Koren 

 and Danielssen, who give the largest numbers, say that 

 variations from 6 to 800 occur in Buccinum undatum. 

 Our counts have given from 49 up to 2,419 ! Moreover, 

 the high numbers were by far the most common. Few 

 capsules contained less than several hundred eggs. In 

 what must be regarded as a very small clump of egg 

 capsules (about 2 cub. inches) we calculated that there 

 must be about 200,000 eggs. 



It is a well-known fact that the number of young 

 whelks leaving the capsules is very much smaller than 

 the number of eggs placed therein. Here again, the 

 figures vary, but the average is probably somewhere 

 around the figure 10. Each capsule is penetrated by a 

 small oval hole, which appears always in the same place, 

 near one margin of the flat side (fig. 61). 



The eggs are 0'25 mm. in diameter, the young shells 

 at the time of leaving the capsules are 3 mm. from the 

 tip of the spire to the end of the siphon, and three 

 whorls are present of rapidly increasing size. 



The embryology of the whelk must be left for a 

 separate work, any consideration of it in a detailed 

 manner would be beyond the usual limits of a memoir of 

 this kind. Koren and Danielssen, in the " Fauna 

 littoralis Norvegiae," were probably the first to describe 

 the sequence of events taking place in the egg capsules. 

 Their account is extremely interesting, though the 

 treatment was naturally limited by lack of the methods 

 now available for embryological research. The eggs 

 when laid are imbedded in a perfectly transparent 

 viscous mass. As development takes place, this albumen 

 becomes less and less viscous, and the eggs become 

 crowded together. Now, according to Koren and 



