274: Agassiz — Albatross Expedition to the Eastern Pacific 



o. 



Art. XXI Y. — On the Progress of the Albatross Expedition 

 to the Eastern Pacific ; by Alexander Agassiz. 



[Extract from a letter to Hon. George M. Bowers, U. S. Fish Commissioner, 

 dated Chatham Island, Jan. 6, 1905.] 



We left Callao for Easter Island Saturday afternoon, 

 December 3 ; as far as 90° west longitude we remained in 

 the Humboldt current, as we could readily see from the 

 character of the temperature serials and from the amount of 

 pelagic life we obtained from both the surface and the inter- 

 mediate hauls. This current also affected the bottom fauna, 

 which was fairly rich even as far as 800 miles from the shore 

 while we, remained within the limits of the northern current. 

 As soon as we ran outside of this the character of the surface 

 fauna changed ; it became less and less abundant as we made 

 our way to Easter Island, the western half of the line from 

 Callao becoming gradually barren. This current also affected 

 the deep-sea fauna to such an extent that towards Easter 

 Island, at a distance of 1,200 to 1,400 miles from the South 

 American continent, our trawl hauls were absolutely barren; 

 the bottom of the greater part of the line was covered with 

 manganese nodules on which were found attached a few insig- 

 nificant siliceous sponges, an occasional ophiuran, and a few 

 brachiopods or diminutive worm tubes, the same bottom con- 

 tinuing to Sala y Gomez and between there and Easter Island. 

 Sala y Gomez and Easter Island are connected by a ridge on 

 which we found 1,142 fathoms near Sala y Gomez, and 1,696 

 fathoms between that point and Easter Island. The ridge 

 rises rapidly from about 2,000 fathoms, the general oceanic 

 depth within about 100 miles, to over 1,100 fathoms within a 

 comparatively short distance from both Sala y Gomez and 

 Easter Island. 



The southern part of our line from Easter Island to the 

 Galapagos shows all the features characteristic of the western 

 part of the line from Callao to Easter Island ; like the latter, 

 as far as the 12th degree of southern latitude it proved com- 

 paratively barren, the bottom consisting of manganese nodules 

 to within about 250 miles of the Galapagos. The pelagic and 

 intermediate fauna from Easter Island to 12° south latitude 

 was very poor, and the serial temperatures show that we were 

 outside and to the westward of the great Humboldt current. 

 But near the 12th degree of southern latitude a sudden change 

 took place ; the pelagic and intermediate fauna became quite 

 abundant again and soon fully as rich as at any time in the 

 Humboldt current. There was also a marked change in the 

 temperature of the water as indicated by the serials, showing 

 that from the 12th degree of southern latitude to the Gala- 

 pagos we were cutting across the western part of the Humboldt 



