SANDER RANG. 579 



" This table is important, were it only to prove that the 

 usual divisions of the more typical bivalves according to the 

 number of their muscles, -whether one or two, is not a 

 natural arrangement ; because it destroys the beautiful 

 analogy which is found to exist in the two typical tribes of 

 the Dithyra and the Gasteropoda, and is not borne out by 

 the details of their analysis." This is a mode of reasoning 

 not likely to impose upon you ; for the " petitio principii " 

 will only be granted to Mr. Swainson by a devotee of his own 

 sect, — a sect always a small one, and now on the decrease. 

 Indeed, I am not aware that any conchologist has adopted 

 Mr. Swainson's method, or made an attempt to complete 

 it by a review of those orders which he left uninvestigated ; 

 and yet such a review you might undertake advanta- 

 geously to task at once your ingenuity and the amount of 

 your newdy acquired knowledge. In the meantime, you 

 will find the " Treatise on Malacology^ " well deserving a 

 perusal ; it is an interesting work in many respects, and is 

 beautifully illustrated. 



I now return to Cuvier, whose system, in 1829, received 

 more applicableness to practice, and an admirable exposition, 

 from the hand of M. Sander Rang, a distinguished officer 

 of the French marines. The following is a synopsis of the 

 classification as proposed by him.* 



MOLLUSCA. 

 Class CEPHALOPODES, Cuvier. 

 Order I. Cryptodibranches, Blainville. 



Fam. 1. OcTOPODES, Leach. Genera — Argonauta, 

 Bellerophon, Octopus, Eledon, Loligopsis. 



Fam. 2. Decapodes, Leach. Genera — Cranchia, Se- 

 piola, Onychoteuthis, Loligo, Sepioteuthis, Sepia. 

 Order II. Siphoniferes, D'Orbigny. 



Fam. 1. Spirules, D'Orbigny. Genus — Spirula. 



Fam. 2. Nautilaces, D'Orbigny. Genera — Nau- 

 tilus, Lituitus, Orthoceratites. 



Fam. 3. Ammones, Lamarck. Genera — Baculites, 

 Hamites, Scaphites, Ammonites, Turrilites. 



Fam. 4. Peristelles, D'Orbigny. Genera — Ich- 

 thyosarcolites, Belemnites. 



* Manuel de I'Histoire Natuiclle dcs Mollusques et de leurs coquilles, 

 ayant pour base de classification ccUc de M. Ic Baion Cuvier. Paris, 1829 

 Duod. 



p p 2 



