MOLLUSCA. 53 



Patella. 



Corpus testa univalvi penitus obtectum ; capite tentacu- 

 lis duobus acutis, basi externa oculferis. Branchiae infra 

 veli marginem per totam corporis periphaeriam seriatim dis- 

 positae. Orificia pro generatione et ano ad latus dextrum 

 anticum. 



Testa univalvis, non spiralis, animal obumbrans, clypi- 

 ata vel retuso conica, imperforata ; fissura marginali destitu- 

 ta ; cavitate simplici ; apice anterius recurvo. 



In this manner the generic character is dependent equally 

 on the shell and the contained animal, and that genus in a 

 system is consequently not sufficiently established in which 

 both these characters are not included. How many genera 

 are in this imperfect state ! Were the same plan followed 

 in the description of species, everything we could wish for 

 would be detailed ; and our knowledge of the forms of mol- 

 luscous bodies would approach to perfection. How much is 

 it to be wished that this plan of Lamark's were generally 

 adopted in this country ! conchology would assume a new 

 aspect, and the number of his votaries would rapidly increase. 



The reader will have perceived, in the course of the 

 hasty review of those systems which we have enumerated, 

 that we have refrained from making any remarks on their 

 comparative excellence. This deficiency we now propose 

 to supply in the following observations. 



The authors who have arranged testaceous bodies, with- 

 out reference to the animals that reside in them, appear to 

 have mistaken the house for the inhabitant, and the thing 

 formed for the being that produced it. They have torn 

 asunder objects which are closely related, and united others 

 which differ in structure and economy. These are neces- 



