MOLLUSCA. 53 
Patella. 
Corpus testa univalvi penitus obtectum ; capite tentacu- 
lis duobus acutis, basi externa oculferis. Branchiz infra 
veli marginem per totam corporis peripheriam seriatim dis~ 
posit. 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 mo!- 
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~ 
