154 ZOOLOGISCHE MEDEDEELTNGEN — DEEL I. 



branchial regions declivous, with two verrucose tubercles, the one 

 behind the other, and a third transversely elongated one just before 

 the lateral end of the hinder transverse groove ; external orbital 

 angle and first lateral tooth not much differing in size and separated 

 by a narrow incision. M. crassipes. 



12. Outer surface of the palm of the male cheliped granulated in its 

 upper part, smooth beneath, with a strong rim running close to and 

 parallel with the under margin, inner surface of the palm and of the 

 fingers hairy, mobile finger without larger tooth at the cutting margin ; 

 breadth of carapace more than twice its length. M. consobrinus. 



The whole outer surface of the palm of the male cheliped with 

 small scattered granules, larger granules arranged in a row parallel 

 with the under margin, inner surface of the palm naked, that of the 

 fingers hairy, mobile finger with a small, but distinct quadrilateral 

 tooth at the cutting margin near the base of the finger; breadth of 

 carapace in adult specimens nearly exactly twice its length, in young 

 specimens less broad. M. convexus. 



13. Inner surface of the palm of the male cheliped with a distinct spine ; 

 a horny crest („musical ridge") close to the inner margin of the arm 

 (meropodite) of the cheliped; outer part of the under margin of the 

 orbital groove with two oblique tubercles. M. erato. 



Inner surface of the palm of the male cheliped without spine, a „musical 

 crest" at the arm of the cheliped maybe present, but is mostly wanting. 14. 



14. Sides of the carapace with four teeth, including the external or- 

 bital angle. 15. 



Sides of the carapace with three teeth (the last one very small), 

 including the external orbital angle. 16. 



15. Carapace (at least in adult specimens) nearly subquadrangular, length 

 to greatest breadth about as 1 : 1.50 — 1.60, closely covered with 

 conspicuous rounded granules and (in young specimens) also with 

 hairs. M. latreillei. 



Carapace somewhat broader, length to greatest breadth about as 

 1 : 1.67, smooth and glossy, except towards the branchial regions, 

 where there are two longitudinal rows of obtuse tubercles, no hairy 

 covering, sides distinctly convergent distally. M. dentatus. 



16. Greatest breadth of carapace between the outer orbital angles (some- 

 times subquadrate). 17. 



Carapace narrowed anteriorly, so that the greatest breadth is lying 

 between the tips of the first lateral teeth, or farther behind, on each 

 branchial region two parallel, longitudinal rows of closely placed 

 larger granules (except in the small M. crinitus). 20. 



