COMMON SHORE-CRAB. 



77 



inner angle. The latero-anterior margin has four strong 

 flattened triangular teeth, directed forwards ; the second 

 and fourth more acute than the others. The latero-pos- 

 terior margin extends backwards in a straight line, and 

 the posterior margin has a distinct elevated waved border. 

 The external antennae are placed in a hiatus at the inner 

 canthus of the orbit, which they do not entirely fill. 

 The basal joint is rather narrow, and somewhat round. 

 The internal antennae are lodged rather obliquely in large 

 open fossae. The anterior pair of feet nearly equal, the 

 wrist with a strong but not very prominent tooth at the 

 upper and anterior angle ; the hand smooth externally, 

 the upper margin with a double longitudinal carina ; 

 the fingers toothed. The second, third, and fourth pairs 

 slightly compressed, the terminal joint very long, styliform, 

 somewhat four-sided ; the fifth pair more compressed, the 

 terminal joint broader and flatter than in the others, form- 

 ing an approximation to the more perfectly natatory form 

 observed in the other genera of the family. The two last 

 joints of the second pair, and the three last of the fifth 

 pair, ciliated on the under edge, and the latter also on the 

 upper edge of all the joints. The abdomen, in the male, 

 five-jointed, forming a slightly acute triangle from the 

 base of the third joint ; in the female, it is seven-jointed, 

 broad, with rounded and ciliated margins, the terminal 

 joint rather abruptly smaller than the preceding. 



The general colour of this species is a blackish green, 

 darker anteriorly, and often dull red underneath ; they 

 vary, however, considerably, both in the hue and in the 

 intensity of the colour. The young are often mottled with 

 white, and sometimes almost wholly white, with perhaps 

 a single black spot on the centre of the carapace. 



This is the only known species of the genus, and is 



