[167]

St Julian tuff ─ pumice tuff obscured by gypsum.─ very rich in siliceous organism ─ irregular organic 1/10 of mass ─ same at Port Desire & St Julian ─ organic part smaller at new Bay = 28 species, 21 new known 7 new = sea-forms are found─ never before found by him in volcanic masses = Chalk Calcareous-form have not appeared in the mass ─ // wants more information on gypsum want an lb inch; I will send joyfully pieces from every locality: E

Pampas formation

= Both certainly contain infusoria = mud fr Patagonian Bahia Blanca Pampas has 3 polygastrica 6 phtolithara which are sweet-water except one, marine, hence [2 words illeg] or perhaps brackish water = mastodon-tooth 7: Polygastric

13 Phytolitharia ─ 1/2 sweet-water & 1/2 sea-beast the former rather preponderant =

[South America, p. 111: "Under the microscope, according to Prof. Ehrenberg,* it consists of minute, triturated, cellular, glassy fragments of pumice, with some broken crystals. In the minute glassy fragments, Prof. Ehrenberg recognises organic structures, which have been affected by volcanic heat: in the specimens from this place, and from Port S. Julian, he finds sixteen Polygastrica and twelve Phytolitharia. Of these organisms, seven are new forms, the others being previously known: all are of marine, and chiefly of oceanic, origin. This deposit to the naked eye resembles the crust, which often appears on weathered surfaces of feldspathic rocks; it likewise resembles those beds of earthy feldspathic matter, sometimes interstratified with porphyritic rocks, as is the case in this very district with the underlying purple claystone porphyry. From examining specimens under a common microscope, and comparing them with other specimens undoubtedly of volcanic origin, I had come to the same conclusion with Prof. Ehrenberg, namely, that this great deposit, in its first origin, is of volcanic nature."]

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= glazed obsidian = want = (Pampas earth ─ [illeg] )