INVERTEBRATA 



OF 



MASSACHUSETTS. 



MOLLUSCA. 



The Mollusca * are animals of a gelatinous or semi-fibrous 

 structure, having no solid frame-work or skeleton, and being 

 without jointed limbs. They reside both on land and in fresh and 

 salt water. The variety in their structure, to adapt them to this 

 diversity of habit, is very great ; and their digestive and generative 

 organs are as much varied to constitute them carnivorous and her- 

 bivorous, oviparous and viviparous, as they are in the higher or- 

 ders of animals. 



Though none of the molluscous or soft animals have any thing 

 like a skeleton, and some of them have nothing solid in any way 

 attached to them, yet the great majority have the power of secret- 

 ing a solid structure which serves them as a habitation and a pro- 

 tection. These last animals are called testaceous mollusca, or 

 Testacea, and their habitations we call Shells. 



The arrangement and study of these marble dwellings, so beau- 

 tiful in their models, so inimitable in their external sculpture and 

 coloring, and oftentimes having their interior lined with pearl, 

 constitutes the science of Conchologf. This science is or- 

 dinarily understood to embrace the study of the shells only, with- 

 out reference to the structure and habits of their occupants. 

 This, it will be at once seen, is altogether unphilosophical, — as 

 much so as it would be to characterize any people with whom we 



* The term is here used in the broad sense in which Cuvier employed it, and 

 includes the animals embraced by Blainville in his type Malacozoaria. 



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