502 THE AQUARIAN NATURALIST. 



remarkable contrivance into the interior of the resi- 

 dence of its victim, we need hardly say that the clever 

 house-breaker proceeds at once to help himself to the 

 contents of the larder. 



The eggs of these carnivorous Gasteropods are ex- 

 ceedingly interesting objects, and, from the facility 

 with which they may be procured and nursed in the 

 aquarium, can easily be made to afford an inex- 

 haustible source of delightful amusement to any one 

 who, with a little patience and a microscope, chooses 

 to compare their varied forms, or examine for himself 

 the wonderful mysteries, but half concealed by their 

 transparent shells, connected with the evolution and 

 development of the enclosed young. 



The egg-cases of the common Whelk (Buccinum 

 undatum) are to be picked up on every beach ; they 

 consist of numerous parchment-like capsules, of a 

 compressed globular shape, united together into 

 roundish masses, which in size and general appearance 

 very closely resemble the nests of some humble-bees, 

 and are known upon the coast by the familiar name 

 of "wash-balls." Each of these capsules (ootheca) 

 contains three or four eggs, wherein, when approach- 

 ing maturity, the young are distinctly discernible, 

 already provided with little shells, consisting of about 

 four whorls, and exhibiting to some extent the cha- 

 racter of the adult. The " concamerated nidus " of 

 the Fusus antiquus is still more curiously constructed : 

 it forms an obtuse cone about three inches in height 

 and two in diameter, made up of a number of pouches, 

 in shape somewhat resembling the human nail, con- 

 vex outwardly and concave on the inner side, encased 



