152 DARK UNFATHOMED CAVES OF OCEAN 



order to search for brooding females of Birgus, for 

 I had reason to believe that females in this interesting 

 condition might possibly be found there in the month 

 of December, and in those days we did not know, 

 and were exceedingly curious to discover, what the 

 newly-hatched young of the robber-crab was like — 

 whether it was from the moment of its birth adapted 

 for life on dry land like its parents, or whether, like 

 its more remote ancestors, it passed through any 

 water-breathing larval stages before betaking itself 

 to a shore-going lile. We unfortunately missed the 

 opportunity of contributing anything to the solution 

 of this exciting question ; but that accomplished and 

 successful naturalist, Dr Arthur Willey, has since dis- 

 covered, when working among the Loyalty Islands, 

 that the female robber-crab hatches its eggs into the 

 sea, and that the young leaves the egg as a zocea, 

 adapted for an aquatic life, like the larvae of ordinary 

 marine hermit-crabs. 



We crossed the Bay to Madras, between the twelfth 

 and thirteenth parallels of latitude, sounding eleven 

 times and dredging three times in deep water on 

 the passage. We found that between the parallels 

 mentioned (12° and 13° N.) and the meridians of 90° 

 and 82° E., the depth of the sea does not vary more 

 than 100 fathoms. In this region, in fact, the floor 

 of the Bay of Bengal is a level plain of chalky paste 

 (Globigerina-ooze) lying a little more than 10,500 feet 



