HARDWICKE'S SCIENCE-GOSSIP. 



253 



struggliug between bis tbumb and finger. In a mo- 

 ment I recalled the caterpillar and its white silken 

 cocoon ; and going to the tree, found the cocoon 

 just emptied, I should say, and this magnificent 

 moth, the transformed green caterpillar of months 



only pay occasional visits to the briny deep. Some 

 observers incline to think that once during the 

 twenty-four hours the Robber Crab enters the 

 ocean, in order to fill the reservoirs on either side 

 of the cephalothorax, by means of which the gills 



Fig. 165. The Walnut Moth (Altacus luna), female; from a specimen in the British Museum. 



gone by. The dark purple band at 

 the front of the superior wings; the 

 clear yellow-green of the wings them- 

 selves: the eye-like spots, and pure 

 white body with purple legs, alto- 

 gether make this " fly " our very hand- 

 somest insect. So, at least, I tliink ; 

 and I wish every one of my English 

 readers who loves butterflies had a 

 fac-simile of the beautiful Attacus 

 luna now lying before me. 



THE EOBBER CRAB. 



{Birgus latro.) 



IT is almost necessary to form some 

 idea of the charming localities 

 met with only in the larger islands of 

 the Pacific, in order fully to understand 

 the interesting habits of the Robber 

 Crab {Birgus latro), which has its abode among 

 them. This curious crustacean, which is also found 

 on the islands of the Indian Ocean, is one of those 

 crabs which can exist for a long time on land, and 



Fig. Kit). Tiie Robber Crab {Birgus latru). 



are kept moist ; other authorities make liis visits 

 less frequent, and probably with greater truth ; but 

 there is no doubt that now and then he recruits 

 his energies by a sea bath. The crab itself is of a 



