CRUSTACEA OF THE LAND 191 



plateau. In many places the soil is honeycombed 

 by its burrows, into which it rapidly retreats when 

 alarmed. These Crabs seem to feed mainly on dead 

 leaves, which they carry in one claw held high over 

 the back and drag down into the burrows. From 

 their enormous numbers, they must play a great part 

 in the destruction of decaying vegetable matter and 

 its incorporation into the soil." 



" Once a year, during the rainy season, they descend 

 to the sea to deposit [or, rather, to hatch out] their 

 eggs, and during this migration hundreds may be 

 seen on every path down steep slopes, and many 

 descend the cliff-face itself. They remain on the 

 beach for a week or two, and . . . afterwards gradually 

 make their way back to their accustomed homes." 



In the year of Dr. Andrews' first visit to the 

 island (1898) this migration occurred in January. 

 On a subsequent visit to the island in" 1908 he 

 obtained specimens of a large Megalopa larva (see 

 p. 70) which occurred in enormous quantities in 

 the sea shortly after the migration, and also of a 

 small Crab which appeared in similar numbers at a 

 slightly later date. It seems practically certain that 

 these larvae and young are those of Gecarcoidealalandii. 

 A second species of Land Crab, Cardisoma hirtipes, 

 found on Christmas Island, has very different habits 

 from the foregoing. Dr. Andrews says of it : " In 

 this island, at any rate, this species must be regarded 

 as a fresh-water form, and, in fact, when a specimen 





