LAND CRABS 79 
granulated and armed with longitudinal rows of spines. 
The pleon of the male usually covers the whole space 
between the bases of the last pair of walking legs. 
These land-crabs are called Towlowroux by the French. 
They inhabit the warm territories of both hemispheres. 
The third maxillipeds suffice without other details to dis- 
criminate the genera. 
Uca, Leach, 1817. The third maxillipeds have the 
fifth joint attached at the outer angle of the fourth; 
the inner edges of the third and fourth joints are 
in one line; along their outer edges the exopod is 
externally visible, and has a flagellum. 
Gecarcinucus, Milne-Edwards, 1842. The third maxilli- 
peds have the fifth joint attached to the middle of 
the apical margin of the fourth ; the inner edges of 
the third and fourth joints are in one line; the 
exopod as in Uca. 
Cardiséma, Latreille, 1825. The third maxillipeds 
have the fifth joint attached at the outer angle of 
the fourth ; the inner edges of the third and fourth 
joints form a re-entering angle; the exopod as in 
Uca. 
Gecarcoidea, Milne-Edwards, 1837. The third maxil- 
lipeds have the fifth joint inserted in a deep groove 
of the apex of the fourth; the inner edges of the 
third and fourth form a re-entering angle; the 
exopod is without flagellum and concealed beneath 
the third joint. 
Gecarcinus, Leach, 1815. The third maxillipeds have 
the fifth joint attached on the inner margin of the 
fourth and completely concealed by it; the inner 
edges of the third and fourth joints form a re- 
entering angle; the exopod as in Gecarcoidea. 
Hyleocarcinus, Wood-Mason, 1874. The third max- 
illipeds have the fifth joint attached to the middle 
of the apex of the fourth ; the inner edges of the 
third and fourth form a re-entering angle; the 
exopod as in Gecarcoidea. 
