AMERICAN NATURAL HISTORY. 3 



HAYES (Aug. A.). On the assumed existence of ammonia in the 

 general atmosphere. — Proc. Amer. Assoc. Adv. Sc. iv. 

 1851, 207. (16 



Lesqtjereux (L.). Account of the swamps existing in the neigh- 

 borhood of many western rivers. — Proc. Bost. Soc. Nat. 

 Hist. iv. 1851, 20. (17 



RICHARDSON (Sir John). Arctic searching expedition ; a journal of 

 a boat voyage through Rupert/ s Land and the Arctic Sea, 

 in search of the discovery ships under command of Sir John 

 Franklin. With an appendix on the physical geography of 

 I^orth America. In two vols. 8vo. London, 1851. 



Richardson (Sir John). On some points of the physical geography 

 of North America, in connection with its geological struc 

 ture.— Quart. Journ. Geol. Soc. L. vn. 1851, 212. (19 



Rogers (H. D.). On the connection of the deposits of common salt 

 with climate. — Proc. Amer. Assoc. Adv. Sc. xv. 1851, 

 ' 126. ( 0 



Silliman (B.) jr. On the mammoth cave of Kentucky. — Amer. 



Journ. of Sc. xi. 1851, 332. (21 



Sqtjier (B. G.). On the volcanoes of Central America, and the 

 geographical and topographical features of Nicaragua, as 

 connected with the proposed inter-oceanic canal. — Proc. 

 Amer. Assoc. Adv. Sc. iv. 1851, 101. (22 



Strachey (Lieut.). On the limit of perpetual snow in the Hima- 

 laya. (Abstract.)— Am. Journ. of Sc. xi. 1851, 244. (23 



GEOLOGY. 



Adams (C. B.). Suggestions on changes of level in North America 

 during the drift period. — Proc. Amer. Assoc Adv. Sc. iv. 

 1851, 60. (24 



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