RELATIVES OF THE OYSTER. 2OI 



were different inhabitants of this portion of the island at 

 some former period. St. Hilaire describes heaps of oyster 

 and other shells, bordering the river Piriqui-assu, near 

 Aldea Velha, which are without doubt kjokkenmoddings. 

 Similar shell-heaps, or Ostreiras, as they are called in 

 Brazil, are found on the coast of Sao Paulo, and on the 

 Ilha do Governador, in the Bay of Rio. They often con- 

 tain human remains, pottery, &c. (h). 



At Castle Hill, near Newhaven, about eight miles 

 from Brighton, immediately beneath the turf, is a regular 

 sea-beach of oyster-shells, many feet in thickness, forming 

 the summit of the chalk cliffs, one hundred and fifty feet 

 above the level of the sea. Near Bromley in Kent, and 

 Reading in Berkshire, similar accumulations of pebbles 

 and oyster-shells are to be found. A layer of oyster-shells, 

 with the valves separated, and exhibiting other marks of 

 water transport, is found, moreover, in the Whitby lias, 

 extending for many miles along the coast, and ten or 

 twelve into the interior. 



During ancient epochs, as we learn from the fossils of 

 both tertiary and secondary strata, many more kinds of 

 oysters lived within our area, and multiplied so as to rival 

 the contents of any modern oyster-beds. In the tertiary 

 system we have a subdivision that is worthy of notice : 

 eocene implies that there will be found the dawn of species 

 still existing ; the miocene subdivision above contains more 

 of the species now living, though extinct species still pre- 

 dominate ; while in the pliocene, or upper division, extinct 

 species decline, and species now living predominate. 



The oysters of ancient times, like those of our own 

 climate, formed by their accumulation banks, more or less 



(Ji) " Scientific Results of Agassiz's Journey," by C. F. Hartt. Note. 



