Page:Geology and Mineralogy considered with reference to Natural Theology, 1837, volume 1.djvu/297

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We may judge of their extent in certain Formations, from the fact, that in the cabinet of Count Munster, there are nearly sixty species collected from a single stratum of the Jurassic Limestone of Solenhofen. A rich harvest, therefore, remains in store for the Naturalist who will trace this interesting subject through the entire series of Geological formations.

The analogies between existing species, and certain fossil remains of Crustaceans have been beautifully illustrated by the investigations of M. Desmarest. From him we learn, that all the inequalities of the external shell in the living specie shave constant relation to distinct compartments in their internal organization. By the application of these distinctions to fossil species, he has pointed out a method of comparing them with living Crustaceans in a new and unexpected manner, and has established satisfactory analogies between the extinct and existing members of this very numerous Class, in cases where the legs and other parts on which generic distribution shave been founded, were entirely wanting.