186 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.37. 



Province iii midsummer varies from 50° F. in the straits themselves 

 to 55° on the Chilean coast in the vicinity of Valdivia. 



The surface temperatures of the Peruvian current, as related to 

 those of the Magellanic water, are therefore warmer; and, as com- 

 pared with the Panamic waters, measurably colder. 



Precisely such a relation to the coast of North America is held by 

 the southerly branch of the North Pacific current, which reaches the 

 coast near Sitka with a summer temperature of 65° to 68°. This has 

 diminished in the latitude of San Francisco Bay to 54° F., but the 

 current continues imtil, in the vicinity of Point Conception, California, 

 it is diverted off shore in a manner entirely analogous to the fate of 

 the Peruvian current at Point Aguja. 



The water of the Panamic Province is less disturbed by currents, 

 receives the full heat of the tropical sun, and, as shown by Dr. Alex- 

 ander Agassiz, emerges from the Gulf of Panama, follows the coast 

 toward Cape San Lorenzo, and is there diverted offshore toward the 

 Galapagos Islands. Trees from the mainland with leaves still adher- 

 ing to them are occasionally cast upon the shores of the Galapagos, as 

 observed by Dr. Agassiz, showing clearly that the current is not only 

 present, but has no inconsiderable motion. The temperature of this 

 water near the coast of Ecuador and only a few miles from the limit 

 of the Peruvian current, in November, varied from 70° to 83° F., and, 

 in March and April from 78° to 85° F. Among the Galapagos Islands 

 the range in April was 81 ° to 83° F. 



It will be noticed therefore that the currents fully account for the 

 peculiarities of the Galapagos mollusk fauna, which exhibits large 

 contributions from the Panamic and Peruvian faunas with only a very 

 unimportant tincture of the Indo-Pacific in its make up. 



A series of surface temperatures measured in November at right 

 angles to the Peruvian current off Point Aguja, by the United States 

 Bureau of Fisheries steamer Albatross, began with a temperature of 

 65° F. close in shore, rose quickly to 69° and later to 70° in the 

 middle of the current, and declined again to 69° F. on its western edge. 



The first exploration of the molluscan fauna of the Peruvian Prov- 

 ince which was systematically carried on was that of Hugh Cuming. 

 He was resident for some years at Valparaiso, later dredged and col- 

 lected vigorously at various points of the Bay of Guayaquil. Tra- 

 dition has handed down the account that a severe earthquake (referred 

 to by Darwin in the Voyage of the Beagle) laid bare a long stretch of 

 coast where the shore mollusks, elevated above their natural situs, 

 were accessible to the collector by the thousand. ]\Ir. Cuming col- 

 lected largely, and on his return to England these collections gave an 

 opportunity to the systematic naturalists to describe many new Peru- 

 vian and Chilean shells. This lasted for a good many years. Broderip, 

 Sowerby, Swainson, Gaskoin, Powys, Deshayes, and Reeve worked on 



