1900.] A Alcock — Carcinological Fauna of India. 387 



79. Elamena (Trigonoplax) ungiiiformis, De Haan. 



Elamene ungiiiformis, De Haan, Faun. Japon. Crust, p. 75, pi. xxix. fig. 1 and 

 pi. H : J. K. Henderson, Trans. Liun. Soc. Zool., (2) V. 1893, p. 394. 



Trigonoplax unyuiformis, Milne Edwards, Ann. Sci. Nut. Zool. (3) XX. 1853,. 

 p. 224: Ortmann, Zool. Jahrb., Syst , VII. 1893-94, p. 31. 



Carapace smooth, flat, lamellar, broadly pentagonal with the 

 posterolateral sides about a third as long as any of the others,_ the 

 regions not defined, the sides entire, unarmed. Front a broad, hori- 

 zontal, triangular lamina. No post-ocular tooth : eyes not concealed by 

 the front, though the eyestalks are. Interantennular septum a mere 

 ridge. 



Epistome as long as broad. Chelipeds and legs smooth and 

 slender. 



Chelipeds not stouter than the legs, about 1£ times as long as the 

 carapace : fingers slender, as long as the slender sub-cylindrical palm, 

 their tips spooned. 



The anterior border of the meropodite of all the legs ends in an 

 iuconspicuous denticle, the dactylus of all is long, subfalciform, and 

 strongly compressed, and has two or three denticles at the tip of the 

 posterior border. The 2ud and 3rd pair of legs, which are the longest, 

 are more than three times the length of the carapace. 



In the Indian Museum are 5 specimens from the Andamans. The 

 carapace of one is 12 millim. long and 14 in greatest breadth. 



Hymenicus, Dana. 



Hymenicus, Dana, Amer. Jonrn. Sci. (2) XII. 1851, p. 290, and U. S. Expl. Exp. 

 Crust, pt. I. p. 387 : Milne Edwards, Ann. Sci. Nat., Zool., (3) XX. 1853, p. 221. 



Differs from Elamena only in the following particulars: — 

 (1) the front is tridentate and the ridge that defines the edge of 

 the carapace dorsally is continued across its base between the eyes : (2) 

 the interantennular septum, as in Trigonoplax, is a mere ridge : (3) on 

 either lateral border of the carapace teeth are sometimes present : (4) 

 the external maxillipeds do not quite meet across the buccal cavern and 

 their exognath is not hidden in its proximal portion. 



Rhynchoplax of Stimpson (Proc. Ac. Nat. Sci. Philad. 1858, p. 109) 

 is probably synonymous. 



Key to the Indian species of Hymenicus. 



I. Median spine of the rostrum of moderate length : 



3 teeth on either lateral border of the carapace ... H, Wood- Mason t. 



II. Median spine of the rostrum very lop g : no teeth on 



the lateral borders of the carapace H. inachoidw. -.- 



