GRAPSOIDEA. 323 



ratio, 1 : 1'22. The sides, as seen from above, diverge somewhat 

 backward, so that the breadth just over the third pair of legs, is 

 twenty-two and a half lines in the female, and twenty and a half lines 

 in the male. Also, the breadth at the anterior angles is twenty lines 

 in the female, and seventeen and a half lines in the male. 



As the species arenaria and rhombea have both hairy legs, and 

 appear to be at times confounded, we describe with some detail the 

 specimens here referred to rhombea. 



Anterior angles of carapax not posterior to any part of the upper 

 orbital margin. Lateral margin fine serrulate. Inferior margin of 

 orbits denticulate. Anterior margin of the arm with irregular spini- 

 form teeth. Carpus mostly smooth on its upper surface. Hand 

 rough granulous on its outer as well as inner surface, somewhat spi- 

 nous above, and spini-dentate on the lower margin ; moveable 

 finger also subspinous. The crest on the inner surface of the hand, 

 near the articulation, naked. Part of hand anterior to fingers, in male, 

 ten lines broad ; length of same to posterior margin of upper half, 

 ten and a half lines ; distance between the lower posterior angle and a 

 point between the bases of the two fingers, eleven and a half lines. 

 In the female, the proportions are about the same, but the hand is 

 smaller (its breadth seven lines), and it is much more nearly smooth. 

 The third joint of the eight posterior legs has smooth sides, and a 

 narrow upper border which is indented and hirsute at the indenta- 

 tions ; in the fifth pair there is also a lower border ; the under side 

 in the second and third pairs especially has its two margins hairy. 

 The fourth joint is sulcate above, especially for the second and third 

 pairs, the margins either side of the sulcus hirsute. The fifth joint of 

 the second and third pairs is densely hairy along a medial line on the 

 posterior surface, as well as on the upper and under margins, and 

 along two or three lines on the anterior surface. The tarsus enlarges 

 somewhat towards its extremity. The male abdomen has the penult 

 segment narrowing slightly towards its apex with a curve, being 

 broadest at its base, and the last segment is oblong triangular. The 

 third joint of the outer maxillipeds is as long as broad, and faintly 

 granulous near the margins. 



Ocypoda rhombea, FABK., Suppl., p. 348 ; EDWARDS, Crust., ii. 6. 



