's RIJKS MUSEUM VAN NATUURLIJKE HISTORIE — LEIDEN. 165 



orbital border, exactly being the same. In M. latipes however the front 

 is broader and very strongly bent downward. 



The Museum does not possess this small species, the carapace of which 

 attains a length of 5 mm., a breadth of 8 mm. A single (male) specimen 

 was dredged at South Mlandu Atoll (Borradaile). 



M. sulcatus H. Milne-Edwards. 



1852. M. sulcatus H. Milne-Edwards. Ann. Sc. nat. sér. 3, Zool., t. 18 p. 156 



(Mauritius). 

 1894. „ sulcatus Ortmann. Zool. Jahrb. Abt. Syst., Bnd. 10 p. 345 



(Australia ?). 

 1900. „ sulcatus Alcock. Journ. As. Soc. Bengal, v. 69, prt 2, p. 379 



(Andamans). 

 1905. „ sulcatus Lenz. Abhandl. Senckenb. Gesellsch., Bnd. 27 p. 366 



(no new record). 



This species seems to have been often confounded with M. grandi- 

 dieri, M. hrevis and M. carinimanus and the synonymy appears the more 

 intricate as under two of the latter names various authors have referred 

 to different species. 



Recently Lenz, who had the opportunity of studying the type-specimens 

 of M. sulcatus and M. grandidieri in the Paris Museum, has clearly given 

 the differences between these species. In M. sulcatus the ocular peduncles 

 are much elongated, reaching (according to Alcock) beyond the antero- 

 lateral angle of the carapace. The outer orbital angle is small and directed 

 somewhat backward; it is crossed nearly at a right angle by the 

 much larger anterior lateral tooth, which projects straightly outward. 

 Upper orbital border less curved than in M. grandidieri. Male cheliped 

 with a high palm, which shows a strong ridge at the outer surface, 

 close to and parallel with the under margin, and at the inner surface 

 there is in the median line a longitudinal row of denticles (according to 

 Alcock), the first one of which, near the carpal joint, is considerably 

 enlarged. Of the fingers the immovable finger only has a strong molari- 

 form tooth near the base. 



Alcock says that the carapace of the males is very broad, the breadth 

 being twice and two-thirds the length, in the females the carapace is 

 somewhat narrower. On each branchial region there are three granular 

 tubercles in a longitudinal row. 



I shall have occasion to note various differences between this species 

 and the following which is very nearly related to it, though, according 

 to Lenz, evidently distinct. 



12 



(l-XII-1915) 



