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MOLLUSCA. 325 
ata vel retuso conica, imperforata; fissura marginali destitu- Mollusca. 
ta; cayitate simplici; apice anterius recurvo. Some 
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 thenumber of his votaries would rapidly increase. 
The reader will have perceived, in the course of the Compara- 
hasty review of those systems which we have enumerated, tive excel- 
that we have refrained from making any remarks on their lence of the 
comparative excellence. This deficiency we now propose *YSt¢™s- 
Mollusea, * Coquille multiloculaire 4 cloisons simples. 
Ned Leurs cloisons ont les bords simples et n’offrent point de sutures 
decoupées et sinueuses sur la paroi interne du test. 
(1.) Coquille droite ou presque droite: point de spirale. 
Les Orthocérées. 
Gen. Bélemnite, Orthocére, Nodosaire, Hippurite, Conilite. 
(2.) Coquille partiellement en spirale ; le dernier tour se continu- 
ant en ligne droit. 
Les Lituoleés. 
Gen. Spirale, Spiroline, Lituole. 
(3.) Coquille semi-discorde, a spire excentrique. 
Les Cristacées. 
Gen. Rénuline, Cristellaire, Orbiculine. 
(4.) Coquille globuleuse, sphéroides ou ovale; 4 tours de spire 
enveloppans ou 4 loges réunies en tunique. 
Les Sphéruleés. 
Gen. Miliole, Gyrogone, Mélonie. 
(5.) Coquille discoide, 3 spire centrale, et 4 loges rayonnantes du 
centre 4 la circonférence. 
Les Radiolges. 
Gen. Rotalie, Lenticuline, Placentule. 
(6.) Coquille discoide, & spire central, et a loges qui ne s’etendent 
pas du centre jusqu’a la circonférence. 
Les Nautilaces. 
Gen. Discorbe, Sidérolite, Polystomelle, Vorticiale, Num- 
mulite, Nautile. 
** Coquille multiloculaire, 4 cloisons découpées sur les bords. 
Les Ammonées. 
Gey. Ammonite, Orbulite, Ammonocérate, Turrilite, Ba- 
culite. 
2. DIVISION. —CEPHALOPODES MONOTHALAMES. 
Coquille uniloculaire, tout-2-fait extérieure, et enveloppant l’animal. 
Gen. Argonaute. 
3. DIVISION.—CEPHLOPODES SEPIAIRES. 
Point de coquille, soit intérieure, soit exterieure. Un corps solide, 
libre, crétacé ou corné, contenu dans lintérieur de la plupart de ces 
animaux. 
Gen. Ponlpe, Calmaret, Calmer, Séche. 
VY. Orpre.—Les HETEROPEDES. 
Corps libre, allongé, nageant horizontalement. Téte distincte ; 
deux yeux. Point de bras en couronne sur la téte; point de pied 
sous le ventre ou sous la gorge pour ramper. Une ou plusieurs na- 
geoires, sans ordre régulier et non disposées par paires. 
Gen. Carinaire, Firole, Phylliroé. 
The authors of the first class of conchologists which we 
haye mentioned, employ exclusively the characters furnish- 
ed by the shell, and scarcely deign to tell us that there is 
an animal attached to that shell. The authors of our third 
class are anxious to keep the shell out of view, and draw 
their distinctions from the animal; but they have failed in 
the attempt. In extreme cases, the characters of the shell 
are resorted to in the absence of distinctions furnished by 
the animal. 
Lamark perceived the inconvenience of separating these 
two modes of examining molluscous animals, and fortunate- 
ly formed a very natural combination. We shall give his 
character of the genus Patella, as a specimen of this mixed 
system. 
Patella. 
Corpus testa univalvi penitus obtectum ; capite tentacu- 
lis duobus acutis, basi externa oculferis. Branchie infra 
veli marginem per totam corporis periphzeriam seriatim dis- 
posite. Orificia pro generatione et ano ad latus dextrum 
anticum. 
Testa univalvis, non spiralis, animal obumbrans, clypi- 
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- 
sary consequences of an artificial system, and they become 
more obvious in proportion as we descend in the scale of 
being. 
The examination of shells, according to this method, may 
be viewed as the study of the osteology of the mollusca. It 
has not for its object the investigation of living matter, but 
of dry bones. Nor has it any of those advantages which 
result from the study of the osteology of the vertebral ani- 
mals. A knowledge of the bones of these animals enables 
us to ascertain many of their primary functions, the nature 
and extent of their powers of motion, and even the food on 
which they subsist. But our knowledge of shells does not 
enables us to say, whether the animal can crawl or swim; 
whether it feeds on plants or animals. The reason is obvi- 
ous. Al] the muscles inserted upon the shell are either 
mere organs of adhesion, or destined to open and shut the 
valves. None of those muscles connected with any of the 
primary organs have any connection with the shell. That 
the shell furnishes several most important characters, we 
readily grant ; but we are here reasoning against the pro- 
priety of attending to the shell, to the exclusion of the animal, 
and, to this extent, our reasoning appears to be conclusive. 
We are aware, that, in the other departments of natural 
history, the appearances which the external parts of an ani- 
mal exhibit are constantly employed in the construction of 
orders and genera, and all the intermediate divisions. Thus, 
for example, the bill, feet, and feathers of birds, furnish the 
characters by which they are arranged in the system. Here, 
however, it must be observed, that the combined informa- 
tion yielded by these parts, makes us acquainted with the 
habits and organization of a bird. By means of these we 
can judge, and with certainty, not merely of its internal 
structure, but the places which it frequents, and the food 
which it consumes. Hence these characters may be appli- 
ed with equal propriety in an artificial as in a natural me- 
thod. But what opinion would we form of that ornitholo-- 
gist, who could readily inform us that the cormorant has 
fourteen tail feathers, and the shag only twelve, but who 
was ignorant of the haunts of these birds, their food, and the 
number of their young. We might prize him as a com- 
panion in surveying a museum, but he is alike a stranger to 
science and nature. 
Nor can we feel more respect for the student of mere 
shells. He may be able to tell us the number of whorls in 
a spiral univalve, or the form of the hinge in a bivalve ; but 
if he knows not the nature of the organs of respiration, di- 
gestion, and reproduction of the animal to which the shell 
