( 139 ) 



It is unusual for the male to possess recognizablt: abdominal appendages 

 other than the telson, but the female has a large biramous appendage on the 

 left side of each of the abdominal somites 2, 3, and 4. The gills are phyllo- 

 branchise and are more or less subsidiary to respiration, which is largely 

 effected by other means. 



The Coenobitidce are land-hermits, visiting the sea occasionally, and in 

 the case of the female periodically to hatch-ofif her eggs. They are character- 

 istic of the tropical Indo-Pacific from East Africa to Panama, but the family 

 is also represented in tropical parts of the Atlantic sea-board, both in America 

 and West Africa. 



The family contains but two genera — Coenobita and Birqus. 



In Coenobita the body is of the common Pagurine form, the carapace 

 being elongate and the abdomen soft and spirally coiled, and the 4th and 5th 

 thoracic legs have the usual Pagurine proportions ; also the rostrum is 

 obsolete. 



In Birgus the carapace, though Pagurine anteriorly, is almost crab-like 

 posteriorly owing to the great development of the gill-chambers ; the abdomen 

 is symmetrical and simply flexed, and is dorsally protected by large, overlap- 

 ping, strongly-calcified terga ; the 4th pair of legs are chelate and are very 

 much longer and stouter than the 5th pair, the latter being usually carried 

 inside the gill-chambers ; and the rostrum is particularly well developed. There 

 is but one species of Birons, B. latro, the " robber-crab," so called from its 

 liking for coconuts, which it was supposed to steal from the trees. 



Coenobita, Latr. 



Coenobita. Latreille, Fam. Nat. du Regne Anim. 1S26, p. 276; and in Cuvier, Rcgne Anim. 

 (2) IV., 1829, p. 77 : Milne Edwards, Hist. Nat. Crust., 11. 1837, p. 238 : De Haan, Faun. Japon. 

 Crust., 1849, p. 203 ; Dana, U. S. Expl. Exp. Crust., pt. I., 1852, p. 435 : Stimpson, Proc. Acad. 

 Nat. Sci. Philad. (1858) 1859, p. 232; Hilgendorf in v. d. Decken s Reis. Ost-Afrika, Crust. 

 111. i. 1869. p. 97 : Boas, Vid. Selsk. Skr., 6 Raek. Nat. o. math. Afd. 1. 2. 1880, pp. US, 190 ; 

 Haswell, Cat. Austral. Crust., 1882, p. 160; Henderson, Challenger Anomura, 1888, p. 50: 

 Bouvier, Bull. Soc. Philomath., Paris (8) II., 1889-90, pp. 143 and 194: Ortmann, Zool. Jahrb-, 

 Syst., VI. 1892, p. 315, and in Bronn's Thier Reich, Malacostraca, p. 1146: Stebbing, Hist. 

 Crust., 1893, p. 159: Borradaile in Stanley Gardiner's Fauna and Geography of the Maldive 

 Islands, I. i., p. 69: Young, Stalk-eyed Crust. VV. Indies, &.C., 1900, p. 358. 



Carapace elongate, more than ordinary contracted and compressed an- 

 teriorly—the contraction and compression involving all the appendages, from 

 the eyes to the external maxillipeds — most strongly calcified anteriorly, but 

 well calcified everywhere except in certain parts of the branchiostegites. 

 Rostrum almost obsolete. 



