162 DB. J. G. DE MAN ON THE PODOPHTHALMOUS 



88. Metaplax dentipes, Heller. (PL XI. figs. 1-3.) 

 Helice dentipes, Heller, Crust aceen der Novara-Reise, p. 62, Taf. v. 

 fig. 5. 



Helice dentipes, Kingsley, Carcinological Notes, no. iv. Synopsis of 

 the GrapsidcB, Proc. Acad. Nat. Sci. Philadelphia, 1880, p. 220. 



This species is represented by a fine series of thirteen speci- 

 mens of various sizes, viz. : one adult male specimen, found at 

 Tavoy, two young individuals from the Eangoon river, two 

 younger individuals from a mangrove-swamp at Zediwon, and 

 eight other specimens from the same locality. 



This species has hitherto been very unsatisfactorily known, as 

 only a young female specimen was described by Heller ; the 

 interesting characters of the male were unknown. The Mergui 

 specimens, however, undoubtedly belong to Heller's Helice 

 dentipes, which may be easily distinguished from the allied species 

 by the less enlarged cephalothorax, by the structure of the infra- 

 orbital ridge, and by some other characters. 



This species is closely allied to Metaplax distinctus, M.-Edw., 

 the upper surface of the cephalothorax in both species being 

 almost similar, but the cephalothorax of M. dentipes is not 

 so enlarged as in M. distinctus, the breadth to the length 

 in the former being as 19 : 14, and in the latter as 19 : 13. The 

 lateral margins present three incisions, so that four teeth are 

 formed ; the first incision is much deeper than the others. The 

 first tooth or external angle of the orbits is a little shorter than 

 the second, whereas in M. distinctus the second is a little 

 shorter than the first. In both species the front is scarcely 

 shorter than the epistome ; the median part of the latter, how- 

 ever, is still visible when the carapace is viewed from above. In 

 the form and the size of the front, and in the structure of the 

 upper surface of the cephalothorax, both species are identical. 



The infraorbital ridge is characteristic of this species, but it 

 differs in the male and in the female. In the male it is continued 

 backwards nearly to, or a little beyond, a point opposite the 

 second lateral incision, and is composed of 25 lobules, of which 

 only six constitute the orbital portion, the remainder being post- 

 orbital. In younger specimens, the lobules which constitute the 

 orbital portion are more numerous. These structures are com- 

 paratively much larger in this species than in M. distinctus, and 

 decrease less gradually but more rapidly in size and length. 

 Each lobule presents at its posterior end a much smaller accessory 



