264 "ALBATROSS" TROPICAL PACIFIC EXPEDITION. 



landed on the first of the islets of the lagoon ; it is entirely made up of 

 fine coral sand and coarse coral shingle, about three feet in height, and 

 perhaps 50 wide, and 100 feet long. Blocks of beach rock conglomerate 

 were scattered in all directions, many of them had been pounded into 

 more or less fine coral sand. From the edge of the beach, extending 

 down into the deeper water of the lagoon, were growing fine coral masses 

 and heads, mainly Madrepores, Pocillipores, and Porites. Very few heads 

 were seen at a depth of sixteen fathoms ; there the bottom consisted 

 entirely of wide lanes of coralline or coral sand separating the few coral 

 heads still left. 



From this island eastward we made a number of soundings in the lagoon, 

 passing gradually from 17 to 11 to 3 fathoms off the lagoon reef flat extend- 

 ing across the gap (Keuea gap) between the principal islands of the south 

 face of Taritari. 



At the gap north of the south horn of Taritari a row of islands runs at 

 right angles to the coi'al shingle beach ; they are covered with cocoanut trees 

 and low brush (Pis. 152, figs. 1, 2; 153; 156, fig. 1). The reef flats con- 

 necting the main islands on each side of Keuea gap are left bare long 

 enough to be used as a wagon road during certain stages of the tide. 



On the lagoon face of the main islands of the land rim extends an immense 

 Millepore flat fully three quarters of a mile in width (PI. 224, fig. 4), and to 

 the west of Keuea gap the flat juts out to a point nearly half-way across the 

 lagoon. The formation of this flat, covered with dead Millepores, over- 

 grown with Nullipores and coralline Algae (Pis. 155, fig. 3; 156, fig. 2), is 

 readily explained by what we observed on the patch of Millepore heads 

 which connects the shore of one of the islets in Keuea gap with the outer 

 sea ledge. On going from the sea beach of the islet north of the gap 

 (PI. 156, fig. 1), towards the outer edge of the reef flat, we come upon a 

 huge dam of large blocks of beach rock and of beach rock conglomerate 

 thrown up on the reef flat (PI. 158, fig. 2), so as to form inside of it, and 

 between it and the eastern beach of the islet, a deep and wide secondary 

 lagoon (PI. 158, fig. 1), in which Millepores are growing in great profusion. 

 The top of the heads of Millepores, as they arose and became exposed to 

 the air and the action of the sea, were gradually killed, and formed a pave- 



