's RIJKS MUSEUM VAN NATUURLIJKE HISTORIE — LEIDEN. 197 



and I think this to be right, also on account of Guérin's statement, that 

 the immobile finger has no larger toothy the very character by which 

 this species is distinguished from the closely related M. japonicus. I agree 

 with de Man (1895) in his doubt about the identity of Haswell's spe- 

 cies with that of Guérin (Haswell himself was not quite certain about 

 his determination), for the palm is described as having „a faint longi- 

 tudinal linear depression close to the lower border", whereas de Man 

 (1888, in Arch. Naturgesch.) expressly states that a ridge or granular 

 row is absent in M. depressus. 



It has been again de Man, who on several occasions pointed out the 

 main characters of this species. The form of the carapace is nearly exactly the 

 same as in M. japonicus, but M. depressus never seems to attain the size 

 of this species. The sides are nearly parallel, not distinctly convergent 

 posteriorly ! )jj the length of the carapace is about two-thirds its greatest 

 breadth, which latter is found between the tips of the first lateral teeth. 

 The whole surface, with exception of the middle parts, is granular, and 

 on the branchial regions there are at each side two longitudinal hairy 

 rows of granules, the outer of which is somewhat convex, a transverse 

 similar row is observed near the insertion of the posterior legs. The 

 outer orbital angle is rectangular and projects less outward than the 

 obtusely rounded anterolateral tooth, which has a convex outer margin 

 and is minutely crenulate; the second tooth is extremely small and sepa- 

 rated from the preceding by a minute incision. Carapace hairy towards 

 the sides, a row of long hairs along the margins. Front narrow, con- 

 stricted, about one-eighth the breadth of the carapace. Upper orbital 

 border nearly straight, under border distinctly and regularly crenulate. 

 Eye-stalks slender, reaching nearly to the external orbital angle. 



In the chelipeds of the male the differences between M. depressus 

 and M. japonicus are clearly pronounced (de Man, 1881). In the first 

 named species the arm is shorter, and the whole inner and outer surface 

 are closely covered with hairs, whereas in M. japonicus such hairs are 

 much more scarcely distributed and arranged especially along the margins. 

 The upper border of the palm is somewhat crenulate in M. japonicus, 

 smooth and slightly granular in M. depressus ; in the first named species 

 the inner surface of the palm and the fingers are naked, or nearly so, 

 the upper surface of the dactylus is granular, and the index bears a 

 large tooth and is curved downward; in M. depressus on the contrary 

 the inner surface of the palm and the fingers are densely hairy, the 



1) De Man (1888, in Arch. Naturgesch.) however has figured the carapace with posteriorly 

 convergent sides. 



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(3-X11-1915) 



