GRAPSOIDEA. 335 



tooth-like projections, between which (the middle and either outer 

 tooth) the inner antennas project. These teeth proceed from the 

 front, just below the front edge of the carapax, this edge appearing to 

 be truncated. The genus Halicarcinus of White, was based upon a 

 species of this kind. Still, others have the front produced and either 

 entire or lobed, and the inner antennas are concealed at base ; these 

 also have the margin of the carapax outside of the orbit, nearly or 

 wholly, without an extra-orbital tooth. Of these species we make the 

 genus Hymeuicus. In all, the carapax is flattened above. In the last 

 two genera, the eyes are situated in orbits, but, like the Periceridas, 

 they are not retractile, so as to conceal the summit or any part of it. 



The genus Hymenosoma occurs at the Cape of Good Hope, Hali- 

 carcinus at Tierra del Fuego and the Falkland Islands, and Hymenicm 

 at New Zealand. 



The species of this family live under, stones along the sea-shore, 

 where washed by the tide. The species of Tierra del Fuego were 

 found abundantly in such positions, and so also those of New Zealand. 



GENUS HALICARCINUS, White. 



Mr. Adam White does not particularly describe the front in giving 

 the characters of his genus, but mentions that it contains the species 

 from the Falkland Islands and that figured by Guerin, which are quite 

 distinct in the character of the front from the species of New Zealand 

 examined by us. We therefore take the Falkland species as the 

 type of his genus, the general outline of which, even to the front, 

 is well represented by Guerin. The margin of the carapax in front, 

 is not directly connected with the teeth, which arise from a somewhat 

 lower level, and often have a softer texture, and a few short hairs at 

 apex. 



The back is either flat or concave, and on the lateral margin there 

 are two distant obsolescent teeth. When these teeth are most pro- 

 minent they appear to consist of three or four slender papillas. 



HALICARCINUS PLANATOS (Fair.}, White. 



Plate 24, fig. la, animal, enlarged; 6, outer maxilliped. 



97 



