30 DE. J. G. DE MAN ON THE PODOPHTHALMOTJS 



GeBus EuxANTHFS, Dana. 



18. EuXANTHrS MAMILLA.TUS, M.-JEdw. 



Cancer mamillatus, Milne-Edwards, Hist, Nat. CrustacSs, p. 3/6. 

 Euxanthus mamillatus, Alph. Milne-Edwards, Nouv. Arch, du Museum 

 Hist. Nat. t. i. p. 292, pi. xv. fig. 2, & t. ix. p. 196. 



Four specimens are in the Collection, two of which were col- 

 lected at Owen Island and two at Elphinstone Island. 



I am inclined, with Milne-Edwards, to regard JEuocantJius 

 melissa, Herbst, E. nitidus, Dana, and E. mamillatus, M.-Edw., as 

 varieties of the same species. An adult male specimen, the 

 cephalothorax of which is 32 millim. long and 49 millim. broad, 

 wholly agrees with the description of true JE. mamillatus, M.- 

 Edw., but in younger specimens, about 21-24 millim. in breadth, 

 the elevations of the upper surface of the carapace are some- 

 what more rugose. I now suspect that in young specimens of 

 these crabs the bosses are always a little rugose, and that they 

 become nearly smooth in adult specimens of JE. mamillatus, while 

 they remain rugose and become even still more so in the form 

 which has been described as JE. Suonii, Lucas. 



Euxanthus mamillatus has hitherto been recorded from the 

 coast of Cochin China and from Australia. 



Genus Xantho, Leach. 



19. Xantho impeessus. Lam. 

 Cancer impressus, Lamarck, I. c. p. 272. 



Xantho impressus, Milne-Edwards, Hist. Nat. Crustach, t. i. p. 393. 

 Xantho impressus, Alph. Milne-Edwards, CrustacSs de la Nouv. CaU- 

 donie, Nouv. Arch, du Museum Hist. Nat. t. ix. p. 198, pi. vi. fig. 2. 



One young male specimen was collected near Owen Island, 

 the cephalothorax of which is 22 millim. long and 38 millim. 

 broad. 



I'his very rare species has been collected also at Mauritius 

 and on the shores of New Caledonia, so that we may conclude 

 that it is distributed throughout the Indian Ocean and the 

 Malayan archipelago. 



