obO MOLLUSKS OF THE GALAPAGOS STEARNS. 



to the mainlaiui. Our kiiowleduo of tlio luaiiin' spocies aloiig- the 

 South Aniorican coast is uot by auy uumus satislactoiy Tho colloo- 

 tiou made by Dr. Joues, of tho V. S, Navy, whiili ouibiai'cd L*ll Wost 

 coast species, oariied 00 of them from 100 to JiJO.l miles farther south 

 thau previously reported. Tcrtariiis, of the Liti>rini(h(\ previously 

 detected at Hood aud l>iudloe by Dr. llabel as listed by Winimer, was 

 subsequently found at ]\[auta, Ecuador by Dr. Jones,* and it is not 

 unlikely that others now rejiarded as peculiar to the Oalapaiios may 

 prove to be mainland forms. Attention is called to my remarks in 

 the eatalog'ue on OmphaliKs Coohwui Smith and its ilose resemblance 

 to, if uot identity with, the Antillean O. /asci{(ti(s. 



The number of species, however, that exhibit intimate relationship 

 with Autilleiin-Oaribbeau forms, is quite small and inconspicuous, when 

 placed side by side with the West Anun-ican types. 



Dini-T :MATEinAL. 



Pertainiui; to the drift material, its quantity aud occurrence, the tes- 

 timony of the sea bed claims special consideration. Keferrino- to the 

 "character of the bottom deposits," Agassiz remarks: '^ Nearly every- 

 where alon.u' our secoud line of exploration, excei>t on the face of the 

 Galapaiit)s slope, we trawled upon a bottom either muddy or composed 

 of Globigerina ooze, more or less contaminated with terrigenous de- 

 posits, ami tVc(iuently covered with a great amount of decayed vegeta- 

 ble matter. We scarcely matlc a single haul of the trawl which did 

 not bring up a considerable amount of decayed vegetable matter, and 

 frequently logs, branches, twigs, seeds, leaves, fruits, much as during 

 our tirst cruise. 



"I was strui'k, while trawling on our secoud line between the Gala- 

 pagos and Acapulco. to observe the great distance from shore to which 

 true terrigenous dei)Osits were carried. There was not a station there 

 occupied of which the bottom could be characterized as strictly oceanic. 

 At our most distant points from shore the bottom specimens invariably 

 showed some trace of a<lmixture with terrigenous material. A very 

 tine mud was the characteristic bottom brought up » * * from 

 depths of 2,000 fathoms. This nuul continued all the way from the 

 Galapagos to Acapulco, and up to the mouth of the Gulf of California, 

 where it became still more an impediment to dredging, so that little 

 work was doiu' until we passed the Tres Marias. Even then the trawl 

 was ordinarily well tilled with mud, and with it came up the usual sup 

 l>lyof logs, branches, twigs, and decayed vegetable nmtter. On going- 

 farther north, into the Gulf of California, the nature of the bottom did 

 not change materially from what it had been along the coast," etc. 



•List of shells collected oa the west coast of South America, principally betweeu 

 latitiules 70- 30' S. and 8-^ 49' N.. by l>r. W. 11. Joues. U. S. Navy. Pioe. U. S. 

 Nat. Mu3., Vol. XIV. pp. 307-335, 1891. 



