142 PROCEEDINGS OF THE ACADEMY OF 



April 7th. 



Isaac Lea, LL.D., in the Chair. 



Thirty-one members present. 



The following was presented for publication : " Description of 

 Sixteen new species of Unio of the United States." By Isaac Lea. 



April 14th. 

 Mr. Vaux, Vice President, in the Chair. 

 Twenty-nine members present. 



April 21st. 

 Mr. Vaux, Vice-President, in the Chair. 



Twenty-four members present. 



The following was presented for publication : 



" Notes on some singular species of Unio." By Isaac Lea. 



A letter from Mr. A. R. Roessler, dated Washington, April 18, was 

 read, stating that he had examined a specimen of tin stone, from the 

 vicinity of Ironton, Mo., and had found it to contain a " very favor- 

 able percentage of metal." 



Dr. Genth remarked that he had examined specimens of the best 

 tin ore of Missouri, and found that they contained only six pounds 

 of tin to the ton of ore. 



April 28th. 

 Mr. Jos. Jeanes in the Chair. 



Forty-three members present. 



The resignation of Mr. Samuel Jeanes, as a member of the Aca- 

 demy, was read and accepted. 



The death of Mr. Isaac Barton was announced. 



The following gentlemen were elected members : Dr. H. C. Chap- 

 man, Mr. Charles Wilson Peale, Mr. Benj. Bullock, Mr. Thos. Web- 

 ster, and Dr. E. Dyer. 



Dr. T. H. Turner, U.S.A., was elected a correspondent. 



On favorable report of the committees, the following papers were 

 ordered to be published : 



On a New MINERAL in CRYOLITE. 

 BY THEO. D. RAND. 



This mineral, for which I propose the name Ivigtite, from its locality, was 

 first observed in 1866, but only recently has been obtained in sufficient quan- 

 tity for examination. 



It occurs disseminated in films and seams through massive cryolite — some- 

 times forming a coating between crystals of carbonate of iron and the cryo- 

 lite in which the carbonate is imbedded. Color pale yellowish-green, some- 



[April, 



