54 INTRODUCTION TO CONCHOLOGY. 



constructor, but deposited from without, with little or no 

 attachment to the animal ; a fact which led to the supposi- 

 tion, that the inhabitant was merely a parasitic intruder, 

 which appropriated this kind of shell to her own use, when 

 the lawful owner was either absent or else unable to defend 

 his rights. Bat at length the real condition of the moUusk 

 was ascertained by the united observations of M. Eang and 

 Madame Power, a lady resident at the port of Messina- 

 Having captured a number of Argonauts, and kept them 

 alive in a large cistern, she observed, not only that eggs 

 were deposited within the shell, but that when, after the 

 lapse of twenty-five days, young Argonauts emerged to Ufe, 

 in twelve days more the two front arms became dilated at 

 the extremity into a pair of membranous webs, and com- 

 menced forming a thin filmy shell. The front arms are, 

 therefore, analogous in their calcifying qualities to the 

 mantles of other mollusks ; and when the creature begins to 

 form her boat, she expands the membrane, and deposits a 

 thin wavy layer of shell matter, working somewhat slowly, 

 yet very surely, till she has moulded a symmetrical boat or 

 car, for the reception of her eggs. M. Eang relates that he 

 saw several living Argonauts wliilst rowing in the port of 

 Algiers, all of which had their arms extended to the sum- 



