314 BULLETIN 103, UNITED STATES NATIONAL MUSEUM. 



ing diagram (fig. 21) ; which is copied from Hedley and Griffith Taylor. 

 Stanley Gardiner has given good descriptions of the faros of the Mal- 

 dives. 1 He says in a footnote on the page referred to: 



The technical term atoll is derlv.-d from the Maldivan atolu, signifying a province 

 for governmental purposes. There are 13 of these in the Maldives, and many consist 

 of the islands on separate banks, most of which have distinct encircling series of reef 

 reaching the surface. Many of the individual reefs are themselves ring-shaped with 

 pools of water several fathoms deep in their centers. There are obvious disadvantages 

 in using diminutives of the terms atoll and lagoon as applying to such. They are 

 situated on shallow banks, and many are actually larger than some of the isolated ring- 

 shaped reefs of the Pacific, which arise separately in the deep basin of that ocean. I 

 therefore propose to borrow further the Maldivan terms, faro and velu, the former 

 signifying such a small ring-shaped reef of an atoll or bank and the latter its central 

 basin. I, further, following the Maldivan use of the term velu, apply it to deep pools 

 even in the long, linear, circumscribing reefs of many of the banks, as I conceive that 

 such pools have in all these reefs on banks the same mode of origin. 



On page 171 of the same work, Gardiner says: 



Each large reef on the bank is a separate entity that has grown up and pursued its 

 history by itself, influenced it is true by the reefs in its vicinity but never directly 

 connected with them. It is only now that the bank is at all approaching the condi- 

 tion J. the perfect atoll. Having seen how small faro may be formed from their 

 earliest beginnings, we now see in North Mahlos the further fortune of such atolls, 

 their joining together where possible to form long linear reefs with the loss perhaps of 

 the whole inner part of their own reefs. 



The second kind of atolls more or less margin and more or less 

 completely, encircle the flat summits of eminences rising from oceanic 

 depths. The Darwinian explanation of the formation of such atoll 

 rings is illustrated by figure 5, page 242, of this paper. Have these 

 atolls formed in accordance with the postulates of the Darwinian 

 hypothesis, or have more or less perfect rings developed on the 

 edges of submarine flats, with or without submergence ? 



The origin of the first kind of atolls has been ascertained with so 

 high degree of probability that it amounts to certainty. They have 

 been formed on relatively shoal submarine flats, during or following 

 submergence, and have been shaped by the prevalent currents. 

 But a basement platform for the second kind of atolls can not be 

 traced beyond the atoll limits, at least in our present state of knowl- 

 edge. However, in case of atolls of an area so large as Rangiroa, in 

 the Paumotus, for instance, the presumption is against their deriva- 

 tion from barrier reefs according to the Darwinian hypothesis. 

 They are too large, and, as Wharton long ago pointed out, their 

 bottoms are too nearly level. If the Darwinian explanation were 

 true, lagoon floors should be concave, more or less bowl shaped. 

 That small, flat, summit areas may result from subaerial degradation 

 and marine planation is known in many instances. That volcanic 



1 Gardiner, J. Stanley, The fauna and geography of the Maldive and Loccadlve Archipelagoes, vol. 1, 

 pt. 2, p. 155, 1901-1903. 



