399 



Fossile Gattungen: 

 Neorthoplilehia Handl. 1908. 



Handlirsch, Fossile Ins. 1906—1908. S. 479. Taf. 42. Fig. 15-18. 



Unterscheidet sich von Bittacus Latr. durch den 3 ästigen hinteren 

 Ast der Media, der sich aber dem ersten Cubitalast angefügt hat und 

 so scheinbar der Gabelast des 1. Cubitus ist. 



4 Species im oberen Lias. 



Psetidopolycentropus Handl. 1908. 

 Handl. 1. c. S. 482. 

 Eine eigenartige Form, durch die sehr kurze Subcosta und den 

 3 ästigen vorderen Medianast von Bittacus Latr. ausgezeichnet. 

 1 Species im oberen Lias. 

 Stettin, 5. Oktober 1909. 



7. The Building of Atolls. 



By F. Wood-Jones, Manchester Universitj". 



eingeg. 8. Dezember 1909. 



1) The reasons why Darwin's theory of Subsidence will 

 not explain the origin of such a structure as the Cocos- 

 Keeling atoll. 



Since the year 1825 the history of the atoll has been well recorded, 

 and in that time the steady tendency of the atoll has been to increase 

 its lagoon shores at the expense of the lagoon water. The lagoon has 

 steadily become more shallow since 1825. Besides this known tendency 

 of atoll building, the structure of the reef and the islands demonstrates 

 that no sinking has taken place in the whole history from the time when 

 the wave washed reef first reached the surface of the sea. The islands 

 are mere débris piles thrown up at intervals upon the level surface of a 

 crescentic reef, — this level rim of the submarine bank I have named the 

 breccia platform. The breccia platform runs under the islands 

 and stretches from the wave-washed barrier edge to the lagoon margin. 

 Since its internal, or lagoon, edge is its oldest part, and in its extent to 

 the seaward edge it represents the building during an enormous period 

 of years, it follows that its lagoon edge should be lower than its seaward 

 edge, if the structure had been sinking. This is however not found to 

 be the case. 



The undermining of coconut palms, and the denudation of shore 

 lines, which Darwin took to be a sign of subsidence, are inconstant 

 features, the outcome of temporary alterations of wind and tide. An 



