The Edinburgh New Philosophical Journal. 263 



into flint-layers, and from the greater decomposition of the calcareous 

 animals, and their conversion into inorganic particles, might thus be 

 assigned to the chalk strata of the north ; but still, local circumstances 

 might produce different effects at the same periods, as is, from other 

 circumstances (from the similar chalk animalcules, &c), more probable. 



" 6. The want of numerous and varied forms of siliceous in- 

 fusory animals in the chalk previously noticed by the author, 

 has now disappeared, and, in its place, great abundance has 

 presented itself. 



" In all, the author has observed seventy-one different microscopic 

 calcareous and siliceous species of animals in the chalk; but, besides 

 these, also numerous larger calcareous animals (l-24th of a line in 

 size) and many included plants, Tethyse, Sponges, Confervae, and Fuci. 

 The varied forms of the genera Rotalia and Textularia of the Polythala- 

 niiae, appear to him to constitute the great mass of the chalk of all lo- 

 calities. He reckons altogether seven genera and twenty-two species of 

 polythalamic microscopic calcareous animals ; and, moreover, microsco- 

 pic and larger nummulites, cypridse, &c. Further, he has hitherto de- 

 termined forty species of siliceous infusory animals which belong to 

 fourteen genera, without including the eight forms previously enumera- 

 ted, and which were probably soft, and merely included in flint. He 

 has found five species of plants containing silica. In the flints of the 

 Jura limestone of Cracow, he detected well preserved peculiar Polytha- 

 lamias, and remains of Sponges or Tethyse ; and lately, he has found Po- 

 lythalamige of the chalk in the flints occurring in the gault which lies 

 under the chalk at Cambridge in England. 



" A general table of these relations of the animals from the chalk and 

 chalk-marl of the fourteen localities observed by him, and also specimens 

 of the rocks, together with a collection of well-preserved microscopic 

 preparations, containing nearly a perfect series of the different species 

 of animalcules, were exhibited to the Academy. 



" To this paper Professor Ehrenberg added a preliminary summary of 

 his examination of the Spiral-corals or Polythalamise, considered in 

 a zoological point of view." 



The next paper on the Extinction of Human Races, by 

 Dr. Pritchard, we shall endeavour to abridge. While other 

 branches of Natural History are diligently cultivated, little 

 attention is paid to Ethnography, while opportunities for 

 pursuing that investigation are daily disappearing for ever. 

 Perpetuity of existence, as far as our ideas of time extend, 



