174 PROF. W. J. DAKIN : EXPEDITION TO THE 



Mangroves rise from the lagoon flat at many points on the shore of 

 Pelsart Island, and they also occur on some of the Northern Islets. This 

 coral flat, however, is not to be found forming the lagoon shore of Pelsart 

 Island along its entire length ; there are many stretches of sandy beach, the 

 sand forming a covering over the limestone flat. 



There remains for further consideration the encircling coral reef to wind- 

 ward of the lagoon. On approaching this barrier at low tide, and from the 

 lagoon, one draws near to a kind of great natural weir over which the ocean 

 water flows almost constantly. The reef is two or three hundred feet across 

 and the surface is smooth and well worn by the water. Few blocks of loose 

 coral are to be found on it and practically no stones to turn over, except 

 where they lie in a hollow — a rock-pool at low tide. Besides these small 

 pools, however, there are largo cavities — great pot-holes. Near the lagoon 

 margin in one or two places were also irregular excavations which were 

 perfect pictures at low tide, for amidst the scattered coral growths were long 

 needle-spined echinoids and thousands of fishes — huge Grropers (Acherodus 

 gouldii) and other species which probably enjoyed the seclusion of these 

 cavities so well supplied with food. The antennre of the large Crayfish 

 Panulirus -penicillatus projected everywhere from the crannies. We have 

 already remarked that there are no islets on the western margin of the atoll. 

 It would appear as if the ocean swell was too powerful to allow any heaping 

 of coral fragments to take place. Broken pieces of coral must be constantly 

 thrown on the reef from the outer face and yet there is no collection of this 

 on the reef itself. The lagoon is noticeably more shallow near this windward 

 side than against Pelsart Island to leeward. Some idea of the force of the 

 waves is apparent from the fact that half the eugine-room and some other 

 sections of a ship, the ' Windsor,' now lie littered on this reef not far from 

 the southern extremity of Pelsart Island. They have been picked up from 

 the bottom outside the reef and thrown on top of it. 



The Fauna of the Pelsakt Group. 



Tbere is little to add regarding the terrestrial fauna of the islands. As 

 mioht be expected, it is poorer than that of the islands of the more 

 northern groups. The bird fauna alone is abundant, and many species were 

 found nesting in considerable numbers, including Mutton-birds, Sooty Terns, 

 Noddy Terns, and Ospreys. Beyond a small lizard, which occurred also on 

 Rat Island, no other vertebrates were observed. 



The marine fauna, on the other hand, was decidedly interesting. In this 

 connection we may mention certain dredge hauls taken in the Zeewyk 

 Channel just north of the Pelsart Group. The bottom was sandy with 

 lumps of worn nullipore and shells. The dredge brought up hundreds of 

 Holothurians of two or three species, one being particularly common. Large 

 quantities of Cidarids were common at the same place, but there were few 



