158 ZOOLOGISCHE MEDEDEELTNGEN — DEEL I. 



The species has hitherto only been found on the continent of British 

 India, it does not seem to occur on the shores of the islands in the 

 Indian Ocean. 



My largest specimen (cf ) has a greatest breadth of carapace of 56 mm., 

 the length is 33 mm. 



M. transversus (Latreille). (PI. Y, Fig, 1). 



1817. Gonoplax transversus Latreille. Nouv. Diet, d'hist. nat., 2 e éd., t. 13 



p. 237 (East-India). 

 1837. M. transversus H. Milne-Edwards. Hist. nat. d. Crust., t. 2 p. 164 



(Pondichéry). 

 1844. „ transversus H. Milne-Edwards. Règne animal d. Cuvier, 2 e éd., 



Crust, pi. 16 f. 2 (no new record). 

 1852. „ transversus H. Milne-Edwards. Ann. Sc. nat., sér. 3, Zool., t. 18 



p. 156 („Mers d'Asie"). 

 1889. „ transversus Cano. Boll. Soc. Nat. Xapoli, t. 3 p. 229 (Massowah). 

 1892. „ transversus de Man. Max Weber's Zool. Ergebn., Brid. 2 p. 308 



(Brandewijnsbaai near Padang). 



Prof. Weber has kindly allowed me to examine the specimen men- 

 tioned by de Man, who has had occasion to compare it with a typical 

 specimen from the Paris Museum. Though the Padang specimen is much 

 damaged and all the legs are detached (though yet present) it enabled 

 me to state that the specimens of the Leiden Museum belong certainly 

 to the same species. As this species is very little known I shall try to 

 characterize it as fully as possible. 



The carapace is more than twice as broad as long and recalls in this 

 respect M. brevis. From the tip of the outer orbital angle to the inser- 

 tion of the last legs the sides are distinctly convergent. The outer orbital 

 angle is pointed, directed straightly outward (in the male from Padang 

 the tip is somewhat curved forward) and separated by a deep incision 

 from the first lateral tooth which is directed somewhat forward and 

 shows a distinct serration on both margins; the second lateral tooth is 

 small but clearly visible and behind it the sides of the carapace are 

 finely denticulated, though this character is somewhat obscured by the 

 hairs at the lateral borders of the carapace. 



The surface of the carapace is in the female specimens of a bluish- 

 grey colour, perfectly smooth and shining, curved in a longitu- 

 dinal direction, but almost straight transversely, except for the very 

 declivous, abruptly sloping sides. On the hepatical and branchial regions 

 there are minute granules. The border of the postero-lateral slopes is 

 marked by a longitudinal row of four or five tubercles (already spoken 



