's RIJKS MUSEUM VAN NATUURLIJKE HISTORIE — LEIDEN ill 



this character the species at first sight resembles somewhat a small 

 Vca (= Gelasimus) and this resemblance is increased by the narrow 

 front *) being much constricted between the eye-stalks, and by the dark 

 green colour of the carapace of nearly all my specimens in spirit-preser- 

 vation. The carapace is nearly wholly smooth and glossy, only towards 

 the sides there are some minute granules. The anterior lateral tooth is 

 much smaller than the external orbital angle and the posterior one is nothing 

 but a faint knob. On the branchial regions there is the same row of 

 verrucous tubercles, three on each side, as we have met with in most of 

 the preceding species. The furrows on the carapace are very faintly 

 marked. The meropodites of the ambulatory legs are robust and armed with 

 a small spine near the distal end of the fore margin, as de Man (1902, 

 p. 494) rightly remarked, except in the case of the hindermost legs, 

 though Stimpson (1907) has here figured a similar spine. 



The chelipeds of the male have been described and figured by de Man 

 in 1888 and again, yet more minutely, by the same author in 1902. 

 There is no need to repeat his statements here ; we may however remind 

 to the fact that, contrary to all the species with short eye-stalks and 

 with a carapace twice as broad as long, M. convexus has no spine on 

 the inner surface of the palm, which is almost wholly naked, only the 

 inner side of the fingers and the neighbouring parts of the palm are 

 fringed with hairs, as has been already stated by Milne-Edwards for his 

 M. inermis. In some cases however the inner surface of the palm seems 

 to be covered with hairs, as both Stimpson, in his final description of 

 the type-specimen, and Alcock state that the hand is hairy within. The 

 outer surface of the palm is very finely granular and bears a faint ridge 

 close to the under margin. Both fingers are armed with a larger tooth 

 at the cutting margin, that of the dactylus being small and quadrangular, 

 the tooth of the index is angular and sloping backward. In young speci- 

 mens these teeth are much less developed than in the adults 2 ) as may 

 be inferred on comparing the chela of M. graeffei (Milne-Edwards, 1873, 

 pi. 13 f. 5 b — 5 C ) and of a young specimen of M. convexus with a breadth 

 of carapace of 16,6 mm. (de Man, 1888, pi. 15 f. 4) with that of a full- 

 grown specimen (de Man, 1902, pi. 19 f. 6), whose breadth of carapace 

 measured 27,5 mm. The fingers are also bent much more downward in 

 the adult. 



The Leiden Museum possesses several specimens, viz. : three specimens 



1) According to de Man (1902, p. 494) the breadth of the front at the fore margin is only 

 2, of the entire breadth of the carapace. 



2) de Man (1902, p. 494) states that in young males, whose breadth of carapace is about 

 14 mm., the teeth on both fingers are already present. 



