274 ALEXANDER AGASSIZ 



not ourselves as yet associated with pirates in the South 

 Seas. The picture, to which we loved to return from the 

 perusal of more trying subjects, showed a low, rakish- 

 looking schooner lying peacefully at anchor in a quiet 

 lagoon surrounded by a circle, deceptively perfect, formed 

 of a narrow strip of land studded with cocoanut palms, 

 under which nestled a few native huts, whose primitive 

 outlines appealed to our imagination. On the outside rim 

 huge rollers, heaped up by the trade winds, beat with 

 savage force. Those of us who, in later years, were for- 

 tunate enough to visit such regions, when a cruel civi- 

 lization had swept away most of the pirates, were sur- 

 prised to find that, fascinating as these atolls were, the 

 perfectly circular land rim of our geographies was the 

 rarest exception. Their form, often most irregular, 

 scarcely ever even approached a true circle. The land 

 rim, seldom continuous, and often broken by gaps of 

 submerged reef or deeper passages, was on the lee side 

 frequently little more than a line of breakers, with per- 

 haps here and there a bit of half-formed land rising 

 along its glistening curve. Sometimes the emerald green 

 of the atoll's quiet lagoon would be bounded only by a 

 white ribbon of sinuous breakers pounding over a con- 

 vex coral reef. 



It is impossible to suppose that these curious coral 

 formations have grown up from the depths of the ocean, 

 since twenty fathoms appears to be about the limit at 

 which reef-building corals usually flourish abundantly. 

 The poet naturalist Chamisso, who, from 1815 to 1818, ac- 

 companied Kotzebue on his voyage around the world, im- 

 agined that atolls grew on the summits of volcanic upheav- 

 als of the bed of the sea, which had reached sufficiently 

 near the surface to permit the corals to obtain a foothold. 



