GRAPSOIDEA. 



GENUS HYMENICUS, Dana. 



Carapax depressus, planus, suborbiculatus. Frons paulo productus 

 breviter obtuse rostratus, aut paulo trilobatus, antennis internis quoad 

 basin carapace omnino tectis. Pedes tenues, manu mediocri. 



Carapax depressed, flat, suborbicular. Front with a short rounded or 

 trilobate beak, the first antennae not being seen in an upper view, 

 the base being wholly concealed beneath the carapax. Feet slender, 

 hand of moderate size. 



In this genus, the front has not the three teeth of Halicarcinus 

 (between which the flexed first antennas are seen), but a simple 

 rounded or trilobate prominence forms the front, and the first antennae 

 are covered. The feet are much longer and more slender than in 

 any of the species of Halicarcinus, seen by the author. As in Hali- 

 carcinus, the eyes are more distant than in Hymenosoma, and there 

 is no prominent extra-orbital tooth, or but a slight one. 



The genus includes the Hymenosoma depressum of Hombron and 

 Jacquinot (Voy. au Pole Sud., pi. 5, f. 34), referred by White to his 

 genus Halicarcinus (Ann. Mag. Nat. Hist., xviii. 178, 1846). 



HYMENICUS YARIUS. 



Carapax Icevis, nudus, planus, ovato-orbiculatus, vix transversus, fronte 

 expansus et trilobatus, margine antero-laterali dentibus duobus obsoletis 

 armato. Abdomen maris angustum, subtriangulatum, segmento primo 

 latiore et utrinque triangulato, penultimo angustiore quam precedens, 

 ultimo paulo oblongo, apicem rotundato. Pedes antici mediocres, octo 

 sequentes tenuissimi, fere aut omnino nudi. 



Carapax smooth, naked, flat, nearly orbiculate or ovato-orbiculate, 

 very slightly wider than long, front projecting and trilobate, antero- 

 lateral margin with two obsolescent teeth. Abdomen of male nar- 

 row, oblong subtriangular, first segment broadest, and triangulate 

 on either side, penult narrower than preceding, last oblong, subtri- 

 angular, rounded at apex. Anterior feet of moderate size, eight 

 following very slender, nearly or quite naked. 



