On a deposit of Bacillaria from Texas and New Mexico 



BY ARTHUR M. EDWARDS, M. D. 



The Llano Estacao, or Staked Plain, as Dana calls it, is a di- 

 strict of Country of considerable interest to the geologist for it is, 

 so to speak, a nut to crack, and has remained so ever since it was 

 traversed, It is out of the way of travel for no raiiroads go across 

 it and no large towns are placed in it. But it is also of conside- 

 rable interest to the microgeologist for he fìnds on it deposits of 

 Bacillaria in the fossil condition, the older « infusorial earths i> of 

 the microscopist of the past which warrants me of saying something 

 about it at the present time. 1 shall also again cali the attention of 

 the general scientist to the story unfinished as it may be of the 

 vast sea, the greatest ocean, a fresh water body of water too, that 

 existed on this continent. 



But first as to the word « fossil » as uscd in this connection. 

 This terni is now applied by geologists to the remains of animais, 

 plants and protista, even to the traces of them, dug out of the earth. 

 Rocks, for that therm was applied to hard substances, but not in- 

 cludes softer things, as day and soil generaly, was found to con- 

 tain something that looked like a shell and was alone known as a 

 fossil. 



The first person that I can find who thought that fossil shells 

 were really shells is an Italian named Cardano who wrote De Sub- 

 tilitate in i552. He decided that petrified shells when found indica- 

 ted the former sojourn of the sea upon the mountains. Palissy, a 

 French writer in i58o considered that the petrified shells found in 

 Italy were deposited by a universal deluge. A belief that has not 

 entirely died out for we tìnd ignorant persons belfeiving it stili. But 



