CUVIER LATREILLE. 549 



ternal or internal, and hence named Gymnocochlides and 

 Cryptocochlides. The limits of the families are circum- 

 scribed by characters derived from the shell, and possess no 

 peculiar merit to detain us in particularizing them. 



The second branch or cryptogamous mollusca are distributed 

 into three classes. The first named PELTOCOCHLIDES em- 

 braces the Scutibranches and Cyclobranches of Cuvier. The 

 second is the BRACHIOPODA, which are either pedunculated 

 or sessile, the character being considered as of ordinal value. 

 The third is the CONCHIFERA, which are classified on the 

 principles of Cuvier, whose families are, however, elevated 

 into the rank of orders. Of these there are four named re- 

 spectively Patulipalla, Biforipalla, Triforipalla and Tubuli- 

 palla, names which have some merit in so far as they indicate 

 the condition of the mantle upon which they are character- 

 ized.* 



On a comparison of these systems you will remark, as their 

 leading principles, that in Cuvier 's the character of the sub- 

 kingdom is derived from the peculiar modification of the 

 nervous system ; the character of the classes from the organs 

 of locomotion, and from the possession of a head ; the charac- 

 ter of the orders from the respiratory organs, and, in the Ace- 

 phales, from the presence or absence of a shell ; and the 

 character of the families from external variations of minor 

 importance but always influential over habits, in the Ace- 

 phales testaces principally from the form of the mantle. 

 Lamarck divides the race at once into two sections from the 

 presence or absence of a head ; and the latter rest their claim 

 to classical distinction on the possession of a bivalve shell ; 

 deriving their ordinal characters from having one or two ad- 

 ductor muscles to close it ; and their families from peculiarities 

 in the form of the foot. The true or cephalous mollusca are 

 divided into orders from the organs of locomotion ; the next 

 sections from the habitat and its co-relative organical peculia- 

 rities ; the subsections from the respiratory organs ; and the 

 families from various sources ; but in the Cephalopods the 

 diagnoses of the primary divisions is derived from peculiari- 

 ties in the formation of the shell. Blainville again has a 

 type and sub-type, the latter dependent on an approach to 

 an annular division of the body. The character of the classes 



* Families naturelles du Regne Animal. Paris, 1825. 8vo, 

 t There is more meant than expressed in the following sentence, written 

 by Cuvier under the provocation of seeing his nomenclature changed un- 

 necessarily : " M. de Lamarck dans son dernier ouvrage, a fait de mes Ace- 

 phales testaces, sa classe des Conchiferes ; et M. de Blainville son ordre des 

 Acephalophores lamellibranches ; metis c\st toujours la meme chose" -Reg- 

 Anirn. iii. 117. 



