iNRODucTioN. Panama Shelh. 17 



by Lieut. Crreen merit especial notice. This officer collected 

 more than 200 species, and carefully noted the habitat of the 

 specimens. Of those which have been determined by Dr. 

 Gould, and which were also found by us at Panama, we 

 have incorporated into the following paper the habitats ob- 

 Tserved by Lieut. Green. This collection proves conclusively 

 that Upper California belongs to a distinct Zoological province. 

 The shells collected by Nuttall in Upper California in 1836, 

 ■and described in the Joixrn. Acad. Nat. Scs. of Philadelphia, 

 VII, in 1837, confirm this inference. None of them are identi- 

 cal with the species which inhabit Panama. 



Narrative of the Expedition. 

 In November, 1850, I left home with the design of spend- 

 ing a few weeks on the Isthmus of Panama, and the remainder 

 of the winter in Jamaica. Leave of absence not having been 

 granted until Nov. 6, the preparations were few and hasty. 

 On the afternoon of the 13th I sailed from New York in the 

 Steamer Empire City, Captain J. D. Wilson,* and on the mori 

 tiing of the 22nd, landed at Chagres. Most of that day was 

 occupied in rambling about the shores. A few shells were 

 found of the same species, which occur throughout the Carib- 

 bean seas. But near Chagres the shores are too much exposed to 

 sustain many species of Mollusks. In the afternoon. Captain 

 Knight, his clerk, and myself hired a boat and started for 

 Cruces, where we arrived on the evening of the 25th. The 



* Since it must be confessed that American naturalists find little sympathy 

 ^ith their pursuits among most of their countrymen of all classes, it affords me 

 the more pleasure to acknowledge my obligations to the owners of the Steamer, 

 Messrs. J. Howard <fe Son, for a passage to Chagres ; and to Oapt. Wilson fof 

 Various attentions on the voyage, and subsequently at the monthly visits of the 

 Steamer to Jamaica. To Capt E. Knight, agent of the Pacific Mail Steam Ship 

 Oo., and my travelling companion across the Isthmus, I was especially indebted 

 ■for unusual facilities in crossing, as well as for other aid. Good company, and the 

 ■extraordinary beauties of nature, more than compensated for four days saturation 

 in mud and water during the transit. 

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