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Scalaria rugulosa, G.B. Sowerby. 10. Pyrula, cast of, like P. ventricosa of Sowerby, Tank Cat. 12. Balanus varians, G.B. Sowerby. 13. Scutella, differing from the species from Nuevo Gulf.
The intermediate variety, consequently, will exist in lesser numbers from inhabiting a narrow and lesser area; and practically, as far as I can make out, this rule holds good with varieties in a state of nature. I have met with striking instances of the rule in the case of varieties intermediate between well-marked varieties in the genus Balanus.
In this species are comprehended three Ascidiæ, of different forms; one Anomia, one Terebratula attached to a Fusus, two Lepas, and a Balanus. Six Holothuria, belonging to three different species, were observed: a large Thalassema gave us a long-wished for opportunity of observing, that this species belongs to the Holothuria, and not to the Annulides.
Venus purpurata, Lam. 14. Venus rostrata, Phillippi. 15. Mytilus Darwinianus, d'Orbigny. 16. Nucula semiornata, d'Orbigny. 17. Cardita Patagonica, d'Orbigny. 18. Pecten tethuelchus, d'Orbigny. 20. Ostrea puelchana, d'Orbigny. 21. A living species of Balanus. 22 and 23. An Astrae and encrusting Flustra, apparently identical with species now living in the bay.
The intermediate variety, consequently, will exist in lesser numbers from inhabiting a narrow and lesser area; and practically, as far as I can make out, this rule holds good with varieties in a state of nature. I have met with striking instances of the rule in the case of varieties intermediate between well-marked varieties in the genus Balanus.
The objects most frequently met with, were an ugly little Turbo, the empty shell of which was tenanted by a black Pagurus and a Balanus. A large Cyanea differs from the European C. ciliata, in the form of the stomach.
Kent, the assistant-surgeon, was so kind as to make for me some measurements with the barometer: he found many marine remains along the shores of the whole bay, at a height of about twenty feet; and from the hill of Sentinella behind Talcahuano, at the height of 160 feet, he collected numerous shells, packed together close beneath the surface in black earth, consisting of two species of Mytilus, two of Crepidula, one of Concholepas, of Fissurella, Venus, Mactra, Turbo, Monoceros, and the Balanus psittacus.
We obtained, at the same time, large pieces of Labularia digitata, Sertularia abietina, upon which nothing of the animal kind was to be seen, but attached to which was frequently found Flustra dentata; also Pagurus Bernhardus, Fusus antiquus, Rostellaria pes pelecani, Cardium echinatum, Ascidia Prunum, Balanus sulcatus, Echinus saxatilis, and Spatangus flavescens.
The mammiferous animals characteristic of this formation, many of which differ as much from the present inhabitants of South America, as do the eocene mammals of Europe from the present ones of that quarter of the globe, certainly co-existed at B. Blanca with twenty species of mollusca, one balanus, and two corals, all now living in the adjoining sea: this is likewise the case in Patagonia with the Macrauchenia, which co-existed with eight shells, still the commonest kinds on that coast.
Trochus, not yet described, but well-known and very common. 17 and 18. Balanus, two species, both common on the coast. These upraised shells appear to be nearly in the same proportional numbers- -with the exception of the Crepidulae being more numerous with those on the existing beach.
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