Vietnam or Thailand ? Vote for the TOP Country of the Week !
Updated: May 26, 2025
But this marvellous structure may be classed as a primary rather than as a secondary sexual character. Although with the Mollusca sexual selection does not seem to have come into play; yet many univalve and bivalve shells, such as volutes, cones, scallops, etc., are beautifully coloured and shaped.
In fact, M. Defrance, in a work* full of new and ingenious ideas, not only recognizes this preponderance of the univalves in the number of the species, but also observes that out of 5500 fossil univalve, bivalve and multivalve shells, contained in his rich collections, there are 3066 univalve, 2108 bivalve, and 326 multivalve; the univalve fossils are therefore to the bivalve as three to two.
It has long appeared to me that in the tropics as well as in the temperate zone the species of univalve shells are much more numerous than bivalves. From this superiority in number the organic fossil world furnishes, in every latitude, a further analogy with the intertropical shells that now live at the bottom of the ocean.
Smith, the conchologist, hoped to pick up some precious univalve or bivalve; Charlie talked of taking a sketch of Cape Cod; Harry declared he was determined to enjoy the trip, as the last holiday he could allow himself for a long time; and Mr. Stryker promised himself the best of chowders, a sea-dish in which he professed himself to be a great connoisseur. Mrs.
At the new salt-works, and at the village of Maniquarez, these stones of the eyes* were offered to us by hundreds, and the natives were anxious to show us the experiment of the lemon juice. It was easy to see that the stones are thin and porous opercula, which have formed part of small univalve shells. Their diameter varies from one to four lines.
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.
If I had worked my way from a sponge instead of a lobster, I should have found it associated, by like ties, with a great number of other animals into the sub-kingdom Protozoa; if I had selected a fresh-water polype or a coral, the members of what naturalists term the sub-kingdom Cælenterata would have grouped themselves around my type; had a snail been chosen, the inhabitants of all univalve and bivalve, land and water, shells, the lamp shells, the squids, and the sea-mat would have gradually linked themselves on to it as members of the same sub-kingdom of Mollusca; and finally, starting from man, I should have been compelled to admit first, the ape, the rat, the horse, the dog, into the same class; and then the bird, the crocodile, the turtle, the frog, and the fish, into the same sub-kingdom of Vertebrata.
If I had worked my way from a sponge instead of a lobster, I should have found it associated, by like ties, with a great number of other animals into the sub-kingdom 'Protozoa'; if I had selected a fresh-water polype or a coral, the members of what naturalists term the sub-kingdom 'Coelenterata', would have grouped themselves around my type; had a snail been chosen, the inhabitants of all univalve and bivalve, land and water, shells, the lamp shells, the squids, and the sea-mat would have gradually linked themselves on to it as members of the same sub-kingdom of 'Mollusca'; and finally, starting from man, I should have been compelled to admit first, the ape, the rat, the horse, the dog, into the same class; and then the bird, the crocodile, the turtle, the frog, and the fish, into the same sub-kingdom of 'Vertebrata'.
It was crammed with shells of every size and description, from the large helmet-conch and Triton's trumpet, down to the tiny pink cowry and rice-volute, all stuffed together without arrangement or packing, forming a mass in which the unbroken shells reposed in a kind of sand, of debris ground together out of the victims; and when she took up a tolerably-sized univalve, quantities of little ones came tumbling out of its inner folds.
There are three varieties, spiral, univalve, and bivalve. In every salt-pan in the country there is a spring of water on one side. I can remember no exception to this rule. The water of these springs is brackish, and contains the nitrate of soda. In one instance there are two springs, and one more saltish than the other.
Word Of The Day
Others Looking