68 MICROSCOPICAL OBJECTS FOUND 



the Mammiferous deposit of the Pampas, at M. 

 Hermoso, from the impure Gypseous strata of the 

 Cordillera of Central Chili, and from most of the 

 specimens from the older Patagonian Tertiary 

 deposits. In those from St. Joseph's Bay 

 were a large quantity of sand grains and much 

 amorphous matter, which latter contained calca- 

 reous elements, along with some calcareous shell 

 prisms. Specimens of soft Sandstone from St. 

 Fe, abounding in extinct shells, consisted chiefly 

 of sand grains, and appeared to contain no cal- 

 careous matter except what was in the form of 

 Droken shells and detached shell prisms. When 

 treated with Nitric acid, there was but little 

 effervescence. 



A singular crystalline limestone from the same 

 locality, reminded me in its aspect, under the 

 microscope, of the Pudding-stones from the 

 Wiltshire green sand, being full of small rounded 

 siliceous granules, only the cementing portions 

 consisted of a crystalline calcareous substance, in 

 which I could not succeed in detecting any micros- 

 copic organizations whatever. It dissolved in 

 Nitric acid with a rapid effervesence,and contained 

 28.54 per cent of Carbonate of Lime. One of 

 the older Tertiary strata from Port Desire, St. 



