692 REPORT — 1901. 



The author meaus to publish a fuller account of the worm elsewhere, and proposes 

 to name it Echinoncma 'jrcvji. 



7. ExUihition of Abnormal Specimens of Neiihrops. By F. H. Marshall. 



8. Exhibition of Microscopic Preparations of Mammalian Hairs. 

 ByV. H, Marshall. 



TUESDAY, SEPTEMBER 17. 

 The following Papers were read : — 



1. '£he Fauna of an Atoll. By C. ForsteR Cooper. 



The island of Holule is a large wooded sand hank placed at the southeiTi end 

 of the eastern reef of Male atoll; it is in no place raised more than three feet 

 above high-tide marks. It shows signs of havhig once been much larger, and of 

 having formerly included the small island of Gadu, now some way to the south. 

 The reefs on the two sides of the island differ from one another in some respects. 

 Tlie eastern and seaward reef is much broader than the western or lagoon reef, and 

 is divided up into three zones, the reef flat, boulder zone, and boat channel, the 

 latter being again subdivided into three zones by the nature of its inhabitants. 



On the western side the boat channel is narrower, and corresponds to the 

 middle zone of the boat channel on the east side ; the reef on this side is more rich 

 than the other. It was found generally that species were often confined to some 

 particular zone ; that where free sand was much washed about by the action of 

 water animals could not and did not flourish. The absence of all seaweeds was 

 also noticeable. 



In the lagoon the bottom was found to consist either of sand or mud, the mud 

 naually being deposited in the centre of the lagoon, where the currents lost their 

 orce. 



Keef-building corals were never found on the bottom of the lagoon, but only on 

 the slopes of reel's. 



The reefs were certainly not extending inwards towards the lagoon, but may 

 perhaps be extending seawards to some small degree. 



2. The Land Crustaceans of a Coral Island. ByTi. A. Borradaile, Jf.^., 

 Lecturer in Natural Sciences at Sehcyn College, Cambridge. 



The island in which the species and their habits were observed was the atoll 

 of Winikoi in the Indian Ocean. 



The following species of Crustaceans are found on land in Minikoi: — 



Crabs : — 1 . Oni/jjode ceratophthalma, greyish-green in colour, and frequenting 

 the lagoon shore, where it lives in spiral burrows below extreme high-water mark. 



2. Ocypode covdimana, chocolate-brown in colour, and living in horizontal 

 burrows on land above extreme high-water mark. 



'6. Geograpsus yrayi, black and white in colour, running about actively in open 

 tpaces. 



4. Geograjisus crinipes, orange-yellow in colour, and living near freshwater 

 tanks and pools. 



5. Geograpsus lonyitarsis var. rninikoiensis, and 6, Metasesarma rousseuuxi, 

 dull greenish in colour, living under timber, stones, &c. 



