NATURAL SCIENCES OP PHILADELPHIA. 147 



then we have had no further trouble with them. When the man was ask?d 

 why he did not s,hoot, he said, ' he did'nt want to shoot the pretty little cree- 

 lers, he wanted to see what they were going to do.' I could not help being 

 pleased with his humanity and love of science." 



Mr. Lea mentioned that he had recently received a letter from Dr. Showalter 

 of Uniontown, Alabama, in which he mentions that specimens of Physa (yyrina) 

 Say, which he sent on, were obtained in an open neglected cistern, and in a 

 trough of water supplied by an Artesian well ten miles from the town. Dr. S. 

 expressed his surprise that these Physa should find their homes so soon at these 

 Artesian wells. There are no streams or pools near to these wells, but in a few 

 years after they are bored and water supplied, these shells may with certainly 

 be found. Mr. Lea went on to mention that he had nearly 30 years ago found 

 an undescribed species of Lymncea, accompained by Physa heterostropha Say, in 

 a small artificial pond on the high grounds near to the Falls of Schuylkill, 

 about four miles north of Market Street, now within the limits of this City. He 

 published an account of it in April 1834, in the Trans. Am. Phil. Soc. under 

 the name of acuta. The pond was small and dug out for lh to 2 feet deep, 

 simply for the supply of rain water for cattle. Afterwards it dried up and the 

 shells were no longer to be obtained there. He never found this Lyvmoea in, 

 any other habitat; but many years subsequently, Dr. Ingalls, of Greenwich, 

 N. Y., near to Lake Champlain, sent him several specimens of what he regard- 

 ed as a new Lymncea, but which was at once recognised as the acuta, heretofore 

 found only in the one habitat near the Falls of Schuylkill. In the minds of 

 some zoologists a difficulty exists as to existence of species in such constricted, 

 isolated points as mentioned above, but that difficulty in Mr. Lea's mind was 

 done away with under the belief that very young molluscs may be transported 

 on the feet of birds from distant points, or on those of cattle going to drink from 

 one place to another. The idea of spontaneous generation could not of course 

 be for one moment admitted. 



Mr. Lea also read an extract of a letter from Dr. Lewis, of Mohawk, 

 N. Y., giving an account of some meteorological phenomena, and exhibited 

 a diagram of thermal curves traced by the self-registering thermometer of Dr. 

 Lewis. 



Prof. R. E. Rogers stated that he had recently received a letter from Western 

 Pennsylvania, communicating the intelligence that some of the Petroleum wells 

 had already begun to show a diminished yield of Oil, a fact in confirmation of 

 an apprehension which lie had expressed at a former meeting of the Academy, 

 that when the Artesian borings became more numerous in the favorite localities, 

 there was a probability of such a result. 



He regarded the circumstance of even a small reduction in the supply of the 

 oil, from any of the wells, at this early stage of the enterprise in that region, 

 as very significant, and suggestive of the fear that, remunerative as these 

 wells may at present prove to be, it may not be prudent to base permanent 

 calculations upon them. 



In connection with the subject, Prof. Rogers described the approved process 

 by which the illuminating and lubricating Coal Oils are manufactured, an I 

 detailed the characteristics which seemed to be requisite to render any oil- 

 making material profitably available for the purpose. 



I860.] 



