294 ZOOLOGY. 



its parasitic habits, as the same remark would apply to 

 most Hermit-lobsters (Paguri) and the marine shells 

 they borrow. The absence of any muscular attach- 

 ment between the Ocythoe and its shell, and the ease 

 with which the animal can liberate itself from its tene- 

 ment and exist uncovered, are also in favour of its being 

 a parasite. Nevertheless, if we reason by analogy, and 

 regard the uniform resemblance in figure that obtains 

 amongst the shells of all the known species of the Nau- 

 tilus family, and how nearly the shell of Ocythoe ac- 

 cords in this respect with those of other testaceous 

 cephalopods which are admitted to be the architects of 

 their dwelling, we shall be better prepared to believe 

 that this creature is not less independent than other 

 testacea of its class ; and this the more readily, since 

 no inferior shell-fish has hitherto been recognised as 

 even a remote claimant for the covering of this species. 

 The investigations of Professor Owen, aided by the 

 enthusiastic researches of Madame Power, (who has 

 availed herself of unusually favourable opportunities for 

 experimenting on living specimens of Ocythoe, on the 

 coast of Sicily,) establish the following more material 

 facts, which may be considered as decisive of this in- 

 teresting question. 



First. " The cephalopod of the Argonaut constantly 

 maintains the same relative position in its shell." 



Second. The expanded membranes on the dorsal pair 

 of arms of this cephalopod resemble the mantle of other 

 shell-fish, and have a like power of secreting materials 

 for the erection or repair of its shell. 



Third. Experiments upon an extensive series of spe- 

 cimens prove, that the weight and measurements of 

 the shell correspond very nearly with those of the con- 

 tained animal, in all stages of its growth. 



Fourth. "The cephalopod inhabiting the Argonaut 



