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"By the marked reduction in the Brachiopods compared with the now richly developed Gasteropods and and sinupalliate Lamellibranchs," it writhed and twisted before his dizzy eyes.
The well-known Strombus luhuanus lives on sand among the reefs at Eagle Island. A Cerithium inhabits mud-flats at Port Molle and Pipon's Islets. Of the holostomatous gasteropods inhabiting the Littoral zone, the Naticae, mostly well-known species, were taken in sandy localities on the north-east coast, and the Neritae in the same province, mostly on rocks or reefs.
We shall always find, that, in proportion as the functions are distinct, and, as it were, individualized by having special organs appropriated to them, animals rise in the scale of structure. The next class of Mollusks, the Gasteropods, or Univalves, with spiral shells, were numerous, but, from their brittle character, are seldom found in a good state of preservation.
On the coast also the Raven seeks to obtain possession of the Hermit-crab. This Crustacean dwells in the empty shells of Gasteropods. At the least alarm he retires within this shell and becomes invisible, but the bird advances with so much precaution that he is often able to seize the crab before he has time to hide himself.
I soon became aware of the force of this rule in the class mollusca, when I first attempted to calculate the numerical proportion of Recent species in the Newer Pliocene formations as compared to the Older Pliocene, and of them again as contrasted with the Miocene; for it appeared invariably that a greater number of the lamellibranchs could be identified with living species than of the gasteropods, and of these last a greater number in the lower division, that of entire-mouthed univalves, than in that of the siphonated.
The larva not only of the carnivorous dytiscus but also of the vegetable-feeding water-beetle are ferocious and carnivorous, and deadly enemies of young fish and ova. In mentioning some of the Thames insecta I have also noticed some of the mollusca and crustacea. It is a pity these have not some common names. One cannot write easily of "pulmonate gasteropods." Mr. Punch.
There are also twelve genera of Gasteropods which have yielded 36 species, four of which pass to the Carboniferous group, namely Macrocheilus, Acroculia, Euomphalus, and Murchisonia. Calceola sandalina, Lam. Eifel; also South Devon. a. Ventral valve. b.
There are 25 Gasteropods and only one cephalopod, Nautilus Freieslebeni, which is also found in the German Zechstein. Spirifera alata, Schloth. Syn. Trigonotreta undulata, Sowerby., King's Monograph. King and Howse.
M. Hornes has described no less than 500 species of gasteropods, of which he identifies one-fifth with living species of the Mediterranean, Indian, or African seas, but the proportion of existing species among the lamellibranchiate bivalves exceeds this average.
There were also armies of garden snails, handsome gasteropods, which were of great interest to me; for I was entering, at this period, upon a passionate pursuit of natural history. For many years I supposed that the odor of the violets proceeded from snails, and to this day I always associate snails with violets, or vice versa.
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