1853.] 379 



and second fingers, which, in the present species are equal in length, whilst in 

 B. boreas the first is longer than the second. The nnembranes uniting the toes 

 are more deeply ernarginate in B. coltnnhiensls, and in which also the sole of the 

 foot is granular instead of being smooth. 



August 16th. 

 Vice-President Bridges in the Chair. 



A communication was read from the Royal Bavarian Academy, dated 

 Munich, 6th Nov., 1853, acknowledging the receipt of the Proceedings, 

 vol. 5, Nos. 9 12 ; vol. 6, Nos. 1 and 2 ] and Journal, new series, 

 part 2 of vol. 2 ; and requesting certain Nos. of the Proceedings defi- 

 cient in their series; also transmitting their publications announced this 

 evenino;. 



Mr. Girard presented two communications by Prof. Baird and him- 

 self, intended for publication in the Proceedings, entitled "Descriptions 

 of Fishes collected by Captains K. B. Marcy and G-e'orge Mc'Clellan, in 

 Arkansas,^' and " Descriptions of new species of Fishes, collected by 

 Mr. John H. Clarke, on the United States and Mexican Boundary 

 Survey, under Lieut. -Col. James D. Graham ;" both of which were re- 

 ferred to Mr. Cassin, Dr. Buschenberger and Dr. Hallowell. 



The following communication was read from Dr. D. D. Owen, dated 

 New Harmony, Ind., August 1, 1852 : 



* After submitting my paper read before the Academy of Natural Sciences, 

 and printed in the Journal, 2d series, vol. 2, pi. 2, Jan. 1853, on a supposed 

 new earth, or a modification of a new one, 1 supplied Dr. Genth with a portion of 

 the mineral, with a request that he would examine it, and let me know thrt 

 result. 



Dr. Genth had no time during my stay in Philadelphia to enter fully into the 

 investigation, but since my return to the west he addressed a letter to me on the 

 subject, which reached this place during my absence from home, which I left on 

 the 15th of June last, and did not return until lately, when the letter was re- 

 ceived. 



I beg leave now to submit the result of his conclusions in regard to it, which 

 are very likely correct, though some of the reactions which I obtained require 

 further investigation, which I propose to undertake when the work I am now en- 

 gaged on shall have been completed. 



Extract of a letter from Dr. Genth to Dr. D. D. Owen : 



" I have just completed the experiments wath your thalia,and have come to the 

 conclusion that it is nothing but magnesia. Magnesia shows sometimes such a 

 strange behaviour with reagents, that one is inclined to think it a new earth. I 

 had the same case wuth my analysis of Kammerite (Rhodophyllite.) It is possi- 

 ble that the relations which exist in the mineral had not been destroyed, and that 

 you have a solution of the mineral, for instance, a solution of aluminate of mag- 

 nesia. I separated both w.th acet. of potash, and free acet. acid and carb. of baryta. 

 The only strange reaction was, that it fell down with NH40,0 in presence of 

 NH4CI, but I find it now in all the magnesian minerals which I examine in a 

 similar manner. 



From the oxalate of your thalia T prepared the pure earth. With cobalt solu- 

 tion before the blowpipe gave it a flesh-colored mass. Dissolved readily in very 

 dilute acid, and gave no precipitate with ammonia, in presence of chlorid ^ 

 of ammonium, and all the reactions of magnesia. The sulphate gave witi* 

 sulphate of ammonia the well known double salt in oblique rhombic prisms. Tiitr- 



