( 149 ) 



The 2nd and 3rd pairs of legs are extremely stout ; the 4th and 5th 

 pairs are cheliform, the 4th being twice as long as and many times more 

 bulky than the 5th which are tucked up within the gill-chambers. 



Abdomen shorter than the carapace, broad, straight, symmetrical^ 

 simply flexed beneath the thorax : all the terga are well calcified, the 2nd 

 3rd, 4th, and 5th being broad overlapping plates with small subsidiary 

 platelets (pleura) on either flank : the 6th tergum and the telson are very 

 much reduced in size, are widely separated from the 5th, and are quite 

 ventral in position. In the male the only abdominal appendages present 

 are those that flank the telson, which, like the telson, are rudimentary, 

 though symmetrical : in the female, in addition, there are large hairy biramous 

 appendages on the left side of the 2nd, 3rd, and 4th abdominal somites. 



The gills, which are phyllobranchiae and are 14 in number on either 

 side arranged as in Pagnrus, are very small, and respiration is chiefly effected 

 by the lining-membrane of the capacious gill-chambers, which is greatly 

 thickened and has its surface enormously increased by abundant arborescent 

 growths. 



The genus Birgus is represented by a single species, the well-known 

 Birgus latto, which, among the tropical islands of the Indo-Pacific, has a 

 range of about 180* of longitude, from the islands in the vicinity of Madagas- 

 car on the west, to the Sandwich Is. and Paumatu (Low) Archipelago on the 

 east. 



Birgus, like the Coenobites, is a fruit-eating — but, on occasion, carni- 

 vorous (scavenging) and cannabalistic — " land-crab," and is a denizen of the 

 jungle, though it is said to visit the shore, and the females must periodically 

 seek the sea to hatch-off their eggs. 



It is essentially a Paguroid (and a Coenobite), being singular only in 

 its gigantic size and in its habits. Its size is such as to render a portable 

 habitation an inconvenience, if not an impossibility, and the requisite 

 protection for its abdomen is supplied by a re-development of the terga, 

 the first five of which are as perfect as those of Pylocheles. Again, by 

 reason of its being an air-breather, its gills, like those of Coenobita, are of 

 only subsidiary importance, and respiration is eff"ected — and herein lies 

 the chief diflference, consequent on a more finished adaptation to a perfectly 

 independent life on land, between Birgus and Coenobita — by an enormous 

 development not only of the gill-chambers themselves, but also of their lining 

 membrane. 



The habits of this remarkable hermit-crab have attracted the attention 

 of many travellers, from the time of Master Francis Fletcher, the chaplain 



