1 LECTURES ON MOLLUSCA. 



plex organization , such as is figured in the beautiful works of Owen 

 and Davidson, from dissections of the existing species. 



For be it observed that shells are not things without life, as they are 

 often taken to be by thoughtless admirers. Nor are they simply the 

 habitations of "shell fish," as ordinary observers consider them. It 

 is common to regard the snail-shell as the house which the creature has 

 made and carries on its back, having a relation to the animal inhabit- 

 ant analagous to that of the coccoon to the chrysalis or the nest to the 

 bird. Even viewed in this light, shells would be most interesting ob- 

 jects of study; representing the different styles of architecture invented 

 by these insignificant mechanics. Such appears to have been the way 

 in which the great Linnasus regarded them ; for he described the ani- 

 mals under other names than those of the shells. Indeed,, he appears 

 to have considered the houses of far more importance than their inhab- 

 itants; for, while he divided the shells into genera and species, he was 

 content to group all the living inhabitants under five names, saying 

 in the description of each genus "Animal a Clio," &c.* Even in his 

 error, however, the great Father of Natural History showed his close 

 discernment; for these five divisions correspond almost exactly to the 

 classes afterwards prepared by Cuvier, and now generally adopted. 



Let it be distinctly understood, therefore, at the outset, that shells 

 are truly organic structures, part and parcel of the living animal, as 

 truly as the nails of man, the plumage of birds, the armor of arma- 

 dilloes and crocodiles, the scales and cartilage of fishes, or the shell of 

 the sea urchin. They are more truly part of the living inhabitant 

 than the skin of caterpillars or the shell of crabs, inasmuch as they 

 are not periodically cast off, but remain, as the hardened skin of the 

 creature, during its whole period of existence. To collect and arrange 

 shells, therefore, bears the same relation to science as to collect and 

 arrange stuffed birds and beasts; in either case we know only a part 

 of the peculiarities of the animal. The mere museum-student would 

 not know the porpoise to be a mammal ; nor discriminate the manatee 

 as being an abnormal pachyderm ; nor observe the wide separation be- 

 tween the horse and the hoofed ruminants. So the mere conchologist 

 would associate the Wendletrap with the top-shells, the nerites with 

 the Naticas, the Cerithiums with the whelks, &c., not knowing that 

 the animals are structurally as much unlike as the mammals just 

 mentioned. It is absurd, therefore, to study shells without examina- 

 tion of the soft parts of the animals; while, to study the soft parts 

 alone, without regard to the differences in the shells, would be like 

 endeavoring to classify the cat-tribe from examination of tigers, pan- 

 thers, &c., which had been previously skinned. 



No one despises a collection of stuffed birds because so few of the 

 creatures have been dissected ; so we ought not to despise the study of 

 shells because we know so little of their inhabitants. But the bird 

 skin tells us much more about the bird than does the shell about the 

 "shell-fish;" because the shell is the hardened skin only of 'a portion 



*The Linnaean Molluscs are Sepia, Limax, Clio, Jlnomia, and rfscidia. The animal ot 

 Terebratula was not then known. 



