-LETTER IX. 



MULTILOCULAR SHELLS .NAUTILUS FOSSIL SPECIES OR- 



THOCERA. 



W E shall now proceed to the examination of the fossil remains of a 

 family of shells, which, whether we consider the greatness 'of their num- 

 bers, the peculiarity of their structure, or the little agreement which 

 exists between the greater part of them and known recent shells, cannot 

 fail strongly to excite our interest and engage our attention. 



These shells are multilocular, being divided into chambers by transverse 

 pierced septa. A communication through the septa distinguishing these 

 shells from those multilocular shells, which have been just examined. 



Very little is known with respect to the animal which inhabits even 

 the recent shells of this description. There is, however, sufficient reason 

 for supposing that the animal resides in the last formed chamber of the 

 shell, and is of the family Cephalapodes. We are indebted for much of 

 this knowledge to M. Peron, who was so fortunate as to obtain the ani- 

 mal of Nautilus spirula in connection with its shell, and brought it, in 

 that state, from New Holland. This animal, which appeared to be 

 analagous with the sepia, had the shell riot only attached to, but so let 

 into its posterior extremity, as to leave a part of it only in view. 



The near agreement of the internal structure of the shell of N. pom- 

 pilius and indeed of most of these many-chambered shells, with that of 



