ACADEMY OF NATURAL SCIENCES. 97 



This fish has great muscular power and can dart very rapidly through the 

 water by lateral vibrations of its tail, at the same time quickly flapping the edge 

 of its disk, to keep its level in the water and to regulate its direction. 



It frequently buries itself slightly' under the mud, and if disturbed obscures 

 the water by stirring the mud, vanishing in the cloud thus raised to hide itself 

 again. It will allow a boat to pass over its place of concealment, and may, if 

 detected, be easily killed by a blow with the end of an oar. Many are also 

 caught in the seines of the fishermen. 



Their food consists of small mollusca, Crustacea and such other animals, alive 

 or dead, as they can obtain. 



Regular Meeting, December 7th, 1863. 

 President in the Chair. 



Present, ten members. 



Donations to Cabinet : 



Rock Salt, from the Upper Colorado River, by F. Ailing. Wood, 

 from near Carson City. 



Dr. Cooper stated that he had received a communication from 

 Mr. P. P. Carpenter, of England, offering to describe any new 

 species of shells from the collections of the State Geological Survey 

 or of the Academy, and to publish the descriptions in its proceed- 

 ings. The Society accepted the proposition. 



Two new sheets of the Proceedings were laid upon the table. 



Regular Meeting, December 21st, 1863. 



President in the Chair. 



Present, seven members. 



Messrs. Royal Fisk and R. L. D'Aumaile were elected resident 

 members. 



Peoc. Cal. Acad., vol. ni. • Jan. 1864. 



