l882. 181 Tratis. N. V. Ac. Set. 



teeth. The modern " white shark " is some five feet long and if 

 the proportion was the same between the size of the teeth and the 

 whole body in the ancient Carcharodon, its size must have been 

 fully fifty feet. It is noteworthy that very large teeth of similar 

 character, but in quite a fresh condition, were dredged up in the 

 depths of the Pacific by the "Challenger" party; which fact would 

 indicate that this species, or one closely akin to it, had survived in 

 the deep waters, at least until quite recently. 



He also exhibited an ingot of aluminium, two inches by six, ob- 

 tained by a new process, at much lower rates than had heretofore 

 been possible, and remarked upon the many important uses for 

 aluminium, if its cost could be reduced. 



The following papers, by Mr. Thomas Bland, were read by 

 title : 



I. DESCRIPTION OF TWO NEW SPECIES OF ZONITES FROM TEN- 

 NESSEE. 



II. NOTES ON THE DISTRIBUTION OF GENERA OF TERRESTRIAL 

 MOLLUSKS IN THE WEST INDIES. 



Dr. Wesley Miller read a paper entitled : 



THE PREVENTION OF TUBERCULAR DISEASE IN MEN AND ANI- 

 MALS BY VACCINATION. 



He discussed the general theory of inoculation and vaccination, and 

 referred to experiments made by himself, and to be further carried on, 

 as to the reduction of virulence attainable by artificial propagation ot 

 virus through many generations, in the bodies of domestic animals. 



Dr. N. L. Britton read the following paper : 



ON SOME large POT-HOLES, NEAR WILLIAMSBRIDGE, N. Y, 



Tne " pot-holes " which I shall attempt to describe were first brought 

 to my notice by the late Prof. A. WOOD. They are located on the 

 western bank of the Bronx River, about midway between Bronxdale 

 and WilliamsDridge, Westchester County, New York. They are near 

 the western end of a now dismantled and impassable bridge, with stone 

 abutments, and in the northern part of a hemlock grove which fringes 

 the stream fjr about a mile below. It is one of the most picturesque 

 spots in the vicinity of New York City, and a walk along the little river 

 from Bronxdale to Williamsbridge is always enjoyable. 



The Bronx " River," as it is called, though the term gives it an im- 

 portance which it does not possess, is a stream about 40 to 50 feet 



