CARCINOLOGICAL STUDIES. 77 



In both species the antero-lateral margins are armed 

 with two teeth behind the acute external orbital angle , 

 of which the anterior one is considerably larger than the third. 



Macr. crassipes and Macr. dilatatus may be distinguished 

 at first sight by the dijBfererit structure of the hands of 

 the male (and probably also of the hands of the female). 

 The upper margin of the arms presents a few small sharp 

 teeth in the middle , in both species , and in both forms 

 the inner surface of the wrist is bispiuose, bearing namely 

 one acute tooth at the inner angle of the upper surface 

 and the other at the inner angle of the under surface. 

 The hands much resemble one another as regards their 

 general form (fig. 7 and 9). The fingers are shorter than 

 the palm and deflexed in both forms. The outer sur- 

 face of the palm (fig. 7) appears nearly smooth 

 for the naked eye in Macr. crassipes', a fine gra- 

 nulation however is observed covering the 

 whole outer surface, when the latter is examined 

 under a magnifying-glass , and these granules increase 

 somewhat in size towards the articulation with the wrist. 

 The upper margin of the palm is finely granulated. ^) In 

 Macr. clilatatxis on the contrary the upper half of 

 the outer surface of the palm (fig. 9) is 

 strongly, though rather thinly, granula- 

 ted, the granules are visible to the naked 

 eye and they are separated by a trans- 

 verse ridge of larger granules from the 

 smooth and concave middle part of the 

 outer surface; that concave part is bordered below 

 by a granulated longitudinal ridge, which proceeds upon 

 the immobile finger, and exists also in Macr. crassipes. 

 The upper margin of the palm bears several prominent 

 and sharp conical teeth in the species of de Haan. The 



]) In oar specimen from the Carolines (fig. Id) the fingers are a little more 

 deflexed and leave, when closed, a somewhat wider hiatus between them than 

 in the Paris type specimen (fig. 7). This slight difference may perhaps be ex- 

 plained by the larger size of the Paris specimen. 



Notes from the Leyden IMuseuixi, Vol. XJI. 



