STALK-EYED CRUSTACEA 51 



Basal spine of external antenn?e long, projecting almost 

 as far as the horns of the rostrum. 



First pair of legs shorter than the second pair ; fourth 

 joint has a row of spines ; hands smooth. Walking legs 

 hairy above, slender ; second and third pairs longer than 

 the carapace ; fourth joint armed above (sometimes below) 

 with a row of spines. 



Range.— St. Thomas. 



2. Pisa. 



Pisa . . . Leach, Milne Edwards, Bell, Miers. 



Cirncer . . . Herbst, Montagu. 



InacJms . . Fabricius, Risso. 



Maia . . . Latreille. 



Carapace rounded behind, with the regions well defined, 

 the gastric region especially. The front is wider than the 

 buccal cavity, and is armed with four horns directed for- 

 wards, of which the two external occupy the anterior 

 extremity of the superior orbital border, and the two 

 middle ones, with diverging ends, form the rostrum, which 

 is always less than one and a half times as long as wide. 



The eyes are scarcely thicker than their stalks. 

 Orbits deep, concealing the eyes when retracted, oval, 

 and directed outwards and downwards ; the superior edge 

 has two clefts separated from each other by a triangular 

 tooth ; their external angle is situated rather below than 

 above the lateral edge of the carapace, which ends here ; 

 below, the orbital border is interrupted by a large hollow. 



The basal joint of the external antennae, much longer 

 than wide, extends beyond the inner canthus of the orbit, 

 but is concealed by the spine from the prolongation of the 

 superior orbital border ; the second joint, frail and cylin- 

 drical, is inserted at about an equal distance from the 



