66 MICROSCOPICAL OBJECTS FOUND 



Mantell has shewn that Foraminifera exist in chi}' 

 obtained from a well at Clapham, and they had 

 previously been observed by Mr. Wetherell in 

 the clay obtained from a well, dug on the south 

 side of Hampstead Heath.* 



Mr. Darwin has kindly obliged me with speci- 

 mens of many of the Tertiary strata brought by 

 him from South America, some of which present 

 singular diflFerences from the majority of those 

 which I had examined from the United States 

 and elsewhere. In none of the specimens 

 examined did I find one Foraminifer, and in 

 only two did T detect any siliceous organ- 

 isms. One of these was the specimen from 

 Port St. Julian, in Patagonia, alluded to in 

 his published Journal, as having been exa- 

 mined by Ehrenberg.f In this deposit, which 

 was part of a stratum eight hundred feet thick, 

 were a variety of siliceous discs, &c. some 

 of them of great beauty, and a few sponge 

 spicula. The substance of which the stratum 

 consisted, is not in the form of rounded sand 



* Trans. Geol. Soc. Second Series. Vol. v. p. 131. 

 f Darwin's Journal of a Voyage round the World. Second 

 Edition, p. 171. 



