's RIJKS M USEUM VAN NATUURLIJKE HISTORIE — LEIDEN. 199 



1897. M. definitus Ortmann. Zool. Jahrb. Abt. Syst., Bnd. 10, p. 342 

 (Philippines). 



1910. „ definitus Rathbun. Buil. Mus. comp. Zool. Harvard Coll., Cam- 

 bridge, Mass., v. 52 p. 307, pi. 2 f. 1 (Makassar). 



Miss Rathbun recently made known the female and it is her descrip- 

 tion and figure we take as base for the diagnosis of this species, which 

 is not in the collection of the Leiden Museum. 



In general appearance M. definitus is again very much related to 

 M. japonicus, but the carapace is broader, the length being three-fourths 

 the greatest breadth, which latter is found rather far behind, behind the 

 lateral teeth; the lateral margins of the carapace are nearly parallel and 

 not at all convergent posteriorly. The whole surface is covered with 

 granules; on each epigastric lobe, immediately behind the base of the 

 front, there is a transverse row of granules, concave forward ; the naso- 

 gastric and cardiac area, besides the neighbouring parts of the hepatic 

 and branchial regions, are smooth, with a polished appearance. There 

 seem to be no longitudinal rows of granules on the branchial regions, 

 but the transverse row at the level of the postero-lateral teeth of the 

 carapace is clearly visible. Front constricted, deeply furrowed, and beaded 

 along the side margins, like the upper orbital border which is straight 

 and elegantly curved. Outer orbital angle rectangular, projecting less 

 outward than the first lateral tooth of the carapace ; the latter tooth with 

 a convex outer margin; second lateral tooth scarcely, if at all, defined. 

 Ocular peduncles slender and short, not reaching the outer orbital angle. 



Male cheliped with a naked under surface of arm (hairy in M.japo- 

 nicus)] upper border of palm coarsely granulate, inner surface densely 

 hairy, as also the inside of the fingers; both fingers with a large tooth 

 at the cutting margin, that on the dactylus however is much smaller 

 than in M. japonicus and that on the immobile finger is lower, much 

 more sloping than in the Japanese species and placed nearly in the 

 middle of the finger, whereas in the other species it is situated nearer 

 to the base. Meropodites of the middle pairs of ambulatory legs narrow- 

 ing towards the distal end, the spine at the anterior border is very 

 small and nearly wholly concealed under the woolly fur with which 

 the meropodites are clothed. There is a transverse ridge on the third ab- 

 dominal segment in the male (in the female also on the preceding segment) 

 which is absent in M. japonicus. 



This apparently very local species has been measured by Miss Rath- 

 bun and for the sake of completeness I give here the dimensions of 

 the two sexes. 



