's RIJKS MUSEUM VAN NATUURLIJKE H ISTORIE — LEIDEN. 167 



The carapace of M. grandidieri is minutely granulated, especially on 

 the branchial and cardiac regions. À second (posterior) lateral tooth is 

 not developed in my specimens but may be concealed under the long 

 hairy covering of the lateral margins. The external orbital angle and the 

 anterior lateral tooth, which latter is very bulky, are placed in a most 

 characteristic fashion (as seen in the figure). Ocular peduncles long ; accord- 

 ing to Lenz they are somewhat shorter than in M. sulcatus, in which 

 species they project slightly beyond the tip of the lateral tooth. Upper 

 orbital margin very convex, minutely beaded. The species is remarkable 

 for the long, slender ambulatory legs, and for the bulky size of the 

 male cheliped. In the latter the palm is very high, higher than in any 

 other species I have seen (see the figure) ; but I must state, that in other 

 specimens the palm is somewhat more slender. On the outer surface there 

 is a distinct ridge, as in many other species af Macrophthalmus, which 

 is proximally finely denticulated but simple on the immovable finger. 

 The fingers are very widely gaping at the base ; the immobile finger 

 has a larger tooth in about the middle of its length, this tooth however 

 is not very much pronounced in my specimens. Milne-Edwards (1868) 

 has also given a figure of the cheliped, in which the fingers are less 

 gaping and each bearing a larger denticulated tooth, that of the movable 

 finger being found near the base and of a quadrangular shape. I have 

 not succeeded in detecting this latter tooth, but my specimens were pre- 

 served in a dry state and the thick hairy coating of the fingers and of 

 the inner surface of the palm has prevented me from getting a distinct 

 view of these parts. The spine at the inner surface of the hand is very 

 conspicuous. The upper margin of the palm is bordered by a regular 

 row of large granules, gradually diminishing in size towards the distal 

 end. Both fingers are very strongly bent inward. 



M. grandidieri is also very nearly related to M. brevis, but in the 

 latter the upper orbital border is not so strongly curved, the outer 

 orbital angle and the anterior lateral tooth keep the same direction and 

 are not placed crosswise, and the palm of the male cheliped is much less 

 high. The ambulatory legs are also shorter in M. brevis. 



The Museum contains four specimens (<ƒ) of M. grandidieri, all in a 

 dry state, from the Red Sea. They had 'hitherto been undetermined. 



The species has only been found at the coast of East-Africa and 

 Madagascar. 



The following is a list of some dimensions of the species in mm. 



