42 peoceedings of the 



The Teopical Pacific. 



It will be convenient to divide the work of this area into three 

 sections, one being the field of operations by the 'Albatross,' the 

 two others by the ' Challenger.' 



1. The Eastern Tropical Pacific. 



Already in 1888, on the outward journey of the 'Albatross,' 

 Captain Tanner took the opportunity of dredging in deep water, 

 twice off the coast of Ecuador, seven times at the G-alapagos, and 

 twice off the coast of Mexico. In the following year he explored 

 the sea round some isolated island rocks lying a considerable 

 distance off the coast, Gruadalupe and E-evillagigedo, which proved 

 to be volcanic peaks surrounded by deep water swarming with 

 fish. He likewise explored the Gulf of California, a work 

 repeated, jointly with A. Agassiz, in 1891. The trawl was used 

 at depths of from 1000 to 1600 fathoms in the central portion of 

 the Gulf. The fauna proved to be unequally distributed, some 

 parts being very poor in life, apparently owing to a large accu- 

 mulation of mud loaded with decomposing vegetable substances. 

 "Where the fauna was rich, it was not found to differ essentially 

 from that of the ocean off the Central American coast. 



At the beginning of the year 1891 Professor A. Agassiz joined 

 Captain Tanner in the ' Albatross,' and the united experience and 

 skill of the two men secured to the cruise of that year most 

 remarkable results ; the number of their dredging stations alone 

 amounts to 76, mostly in very deep water. A lengthened visit 

 was paid to the Galapagos Archipelago : Prof. Agassiz has no 

 doubt of the truly volcanic character of the islands and dispro\ es 

 altogether the idea of their having formed a part of the South 

 American continent. The bottom of even the deepest parts 

 north and north-west of the islands was found to be covered with 

 masses of vegetation in every possible state of decomposition, 

 and the Deep-sea fauna in the vicinity to be remarkably poor. 



The collections made on this cruise led Agassiz to enter again 

 into the question of the relation of the bathy bial faunas of the two 

 sides of Central America. He says * that on the West Coast the 

 Deep-sea fauna is poorer than on the Atlantic side, but that it 

 finds in almost.all classes its parallel in the West Indies; that, 

 for instance, only one species of Echini is found in the Panamic 

 district not previously represented in collections from the Atlantic 

 side ; that this fauna recalls later Cretaceous times when the 

 Caribbean Sea was practically a Bay of the Pacific — a Deep-sea 

 fauna showing relationship on the one side to the Atlantic and 

 West-Indian types, and on the other pointing to the eastward 

 extension of Western Pacific types of wide geographical range, 

 which mix with the strictly deep-sea Panamic ones. 



One of the principal objects of this cruise was to decide the 



* Bull. Mus. Comp. Zool. xxiii. 1892, no, 1. 



