IXTEODUCTIOX. xxix 



depths (324 fathoms) of the southern exten.sioti of the eastern plateau of 

 Fiji, upon which are situated the Lau group of atolls and islands (PI. 220, 

 Stations 189-193, p. 389). 



The Admiralty Charts of Fiji and north of that group contain numerous 

 soundings (PI. 221). As far as practicable we intercalated our soundings 

 with those already published ; we sounded usually within a half or a third 

 of a mile off the different islauds and atolls, as well as in the centre of the 

 channels separating them. We showed that in the Ellice group, as had 

 already been indicated by the " Penguin," the atolls are separated by deep 

 channels (PI. 221, Stations 194, 195, p. 389). We found the same to be the 

 case in the Gilbert Islands (PI. 223, Stations 196-207, p. 389), though some 

 of the atolls (Apaiang, Tarawa, and Maiana) are, as in the Paumotus, united 

 by a comparatively shallow plateau. Over 2500 fathoms separates the 

 Gilbert from the Marshall Islands (Stations 208-212, p. 390) ; the atolls of 

 the Marshall Islands are, like those of the Ellice and Gilbert groups, sepa- 

 rated by deep channels, a few of the atolls (Namu and Odia) being united 

 by shallower plateaus (PI. 225, Stations 213-238, p. 390). 



The islands and atolls of the Carolines are separated by deep water 

 (PI. 232, Stations 239-244, p. 391), and between the Carolines and Guam 

 the United States Steamer '• Nero " obtained, about one hundred miles 

 southeast of Guam, the greatest oceanic depth as yet recorded (5269 

 fathoms). Nothing is known of the submarine slope of the Carolines with 

 the exception of the soundings taken by the " Albatross " a short distance 

 ofT Port Lottin and Nama (Stations 239, 242) ; the depths correspond to 

 those off similar islands in the Society and Gilbert Islands. The sound- 

 ings of the '• Challenger" and of the " Nero" indicate great depths between 

 the volcanic islands of the line extending from Guam to Japan (Pis. 1, 234). 



We took a number of soundings off the atolls of the Paumotus, Gilbert, 

 and Marshall Islands at a distance varying from one mile to a quarter of a 

 mile. These soundings, like those off the Paumotus, varied from 225 to 

 over 400 fathoms, and only showed that at those distances from the shore 

 we had already reached the oceanic slopes of the atolls. The}' all indicate, 

 within those limits, steep slopes in the upper part of the reefs (see the List 

 of Soundings for these groups, p. 379). 



