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In the North-east Australian province we have species of Donax, Mactra and Corbula, all apparently new, from the shallower localities; Corbula tunicata, Pectunculus tenuicostatus, and another, from 8 to 11 fathoms, off Cumberland Islands; species of Arca, Pectunculus, Avicula, Pecten, Venus, Circe, Cardium, Cardita, and Erycina, mostly new, from 15 to 17 fathoms in a sandy and shelly bottom off Cape Capricorn.

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.

Those which I examined near the A. S. Juan were much worn: they consisted of Mactra Isabellei, d'Orbigny, mingled with few of Venus sinuosa, Lam., both inhabiting, as I am informed by M. d'Orbigny, brackish water at the mouth of the Plata, nearly or quite as salt as the open sea.

Kent collected for me some silicified wood and shells out of the concretions in the sandstone from Tome, situated a short distance north of Lirguen. They consist of: Natica australis, d'Orbigny, "Voyage, Part Pal." 2. Mactra Araucana, d'Orbigny, "Voyage, Part Pal." 3. Trigonia Hanetiana, d'Orbigny, "Voyage, Part Pal." 4.

If M. d'Orbigny had been aware of the many long parallel lines of sand-hillocks, with infinitely numerous shells of the Mactra and Venus, at a low level near the Uruguay; if he had seen at Bahia Blanca the immense sand-dunes, with water-worn pebbles of pumice, ranging in parallel lines, one behind the other, up a height of at least 120 feet; if he had seen the sand-dunes, with the countless Paludestrinas, on the low plain near the Fort at this place, and that long line on the edge of the cliff, sixty feet higher up; if he had crossed that long and great belt of parallel sand-dunes, eight miles in width, standing at the height of from forty to fifty feet above the Colorado, where sand could not now collect, I cannot believe he would have thought that the elevation of this great district had been sudden.

Mactra Araucana, d'Orbigny, "Voyage, Part Pal." 12. Arca Araucana, d'Orbigny, "Voyage, Part Pal." 13. Nucula Largillierti, d'Orbigny, "Voyage, Part Pal." 14. Trigonia Hanetiana, d'Orbigny, "Voyage, Part Pal." During a second visit of the "Beagle" to Concepcion, Mr.

I heard, also, of beds of shells on the Somborombon, and on the Rio Salado, at which latter place, as M. d'Orbigny informs me, the Mactra Isabellei and Venus sinuosa are found. Mr. Res." page 35 and Dr.

In the South Australian province species of Mactra, Psammobia, Venus, Tapes and Pecten, all peculiar, were taken. This is the region of the peculiar genus Myadora, of which five species were dredged on sand in 6 fathoms at Port Jackson, along with Myochama anomioides, Trigonia margaritacea, Lima bullata, and Cardium radiatum.

In one collection of these shells, there were some valves of the Venus sinuosa, Lam., the same species found with the Mactra on the banks of the Uruguay. Besides these shells, cellular, highly crystalline rock, formed of the casts of small bivalves, is found near Ensenada; and likewise beds of sea-shells, which from their appearance appear to have lain on the surface.

Fusus difficilis, d'Orbigny, "Voyage, Part Pal." 5. Pyrula longirostra, d'Orbigny, "Voyage, Part Pal." 6. Pleurotoma Araucana, d'Orbigny, "Voyage, Part Pal." 7. Cardium auca, d'Orbigny, "Voyage, Part Pal." 8. Cardium acuticostatum, d'Orbigny, "Voyage, Part Pal." 9. Venus auca, d'Orbigny, "Voyage, Part Pal." 10. Mactra cecileana, d'Orbigny, "Voyage, Part Pal." 11.