Mr Logan on thr Habits of Testaceous Molha^ca. 53 



numbers. It was therefore impossible for me to say whether 

 they were zoophagous or phytophagous. 



It appears to me, that the above facts lead to the following 

 in(£uiries :— 



l*v', Has the period been ascertained at which any of the 

 great family of niollusca begin to exercise their reproductive 

 functions ? 



2(1, Do they all pass certain periods of torpidity before ar- 

 riving at their full growth ? 



Si/, Do they reproduce after each period of rest, or not till 

 they have arrived at then- full growth, or nearly attained to it i 



Ath, After arriving at full growth, how often do they re- 

 produce before ih.eY die ? 



bth, May it not be supposed that, during each of those pe- 

 riods of rest, certain changes are pi-oduced in their organization, 

 which may answer some such end as the pupa state amongst 

 insects ; or at least may effect the purpose of consolidating and 

 perfecting the last new growth which has been hastily sketch- 

 ed out during the feeding period ? 



The determination of the length of the periods during Avhich 

 these animals remain in a state of I'cst or activity, would be 

 highly interesting, and might be easily accomplished by any 

 one residing for a year, or perhaps half that time, in a tropi- 

 cal climate, as there is little doubt that all animals of the 

 same kind and genera have similar habits in the same latitudes 

 throughout the world. 



Zoolof/ical Inst rue t'wtis of the Boyal Academy of Sciences, 

 Paris, for the Scientific Expedition repairing to the North 

 of Europe. Drawn up by M. Isidore Geoffroy Saint 



HiLAIRE. 



Since the year 1732, the date of Linnaeus's celebrated jom'- 

 ney through Lapland, the Scandinavian Peninsula has been 

 many times explored, almost in every part, by distinguished 

 zoologists, or at least skilful collectors. Notwithstanding the 

 zeal of the naturalists belonging to the new Commission, and 

 the favourable circumstances in which they are placed by tiie 



