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 membranes uniting the toes 
are more deeply emarginate in B. columbiensis, and in which also the sole of the 
foot is granular instead of being smooth. 
August 16th. 
Vice-President BripeEs in the Chair. 
A communication was read from the Roya! Bavarian Academy, dated 
Munich, 6th Nov., 1853, acknowledging the receipt of the Proceedings, 
vol. 5, Nos. 9—12; vol. 6, Nos. land 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 
evening. 
Mr. Girard presented two communications by Prof. Baird and him- 
self, intended for publication in the Proceedings, entitled “ Descriptions 
of Fishes collected by Captains R. B. Marcy and George 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. Ruschenberger 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, pl. 2, Jan. 1853, on a supposed 
new earth, cr a modification of a new one, | supplied Dr. Genth with a portion of 
the rear ae with a request that he would examine it, and let me know the 
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 f propose to undertake when the work lam now en- 
gaged on shall have been completed. 
Extract of a letter from Dr. Genth to Dr. D. D. Owen: 
«<T have just completed the experiments with 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 with 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 NH,O,O in presence of 
NH,Cl, but I find it now in all the magnesian minerals which I examine in a 
similar manner. 
From the oxalate of your thalia I 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 chloride 
of ammonium, and all the reactions of magnesia. The sulphate gave with 
sulphate of ammonia the well known double salt in oblique rhombic prisms. The 
