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Updated: July 28, 2025
Throughout this great division of the animal kingdom, as far as I can discover, secondary sexual characters, such as we are here considering, never occur. In the Lamellibranchiata, or bivalve shells, hermaphroditism is not rare. In the next higher class of the Gasteropoda, or univalve shells, the sexes are either united or separate.
He told Charley to put all these shells together in his Museum, because, in certain particulars, they are alike, and all have, besides their own special names, the same generic name of Gasteropoda. They are so called, because they have something like a foot proceeding from the body which they use for moving about.
Thus the Cephalopoda are the most valuable, as having a more restricted range in time than the Gasteropoda; and these, again, are more characteristic of the particular stratigraphical subdivisions than are the Lamellibranchiate Bivalves, while these last, again, are more serviceable in classification than the Brachiopoda, a still lower class of shell-fish, which are the most enduring of all.
Indeed, some of our rock-deposits consist chiefly of the fragments of their remains. The Mollusks were also represented then, as now, by their three classes, Acephala, Gasteropoda, and Cephalopoda. The Acephala or Bivalves we shall find in great numbers, but of a very different pattern from the Oysters, Clams, and Mussels of recent times.
Among such indications I may remind you of the predominance of Holostome Gasteropoda in the older rocks as compared with that of Siphonostone Gasteropoda in the later.
Of the many living Gasteropoda taken in this region, very few are new species. Of Patelloid forms we have a new Fissurella and Parmophorus convexus at Port Dalrymple, accompanied by Haliotis naevosa, and species of Patella and Siphonaria. In the more tropical regions, Haliotis asinina and varia, another and distinct Patella, two Fissurellae and a Scutella were collected.
Among such indications I may remind you of the predominance of Holostome Gasteropoda in the older rocks as compared with that of Siphonostome Gasteropoda in the later.
Besides, it has been clearly established, that one at least of the gasteropoda is furnished with the power of producing sounds. Dr.
Among such indications I may remind you of the predominance of Holostome Gasteropoda in the older rocks as compared with that of Siphonostome Gasteropoda in the later.
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