STALK-EYED CRUSTACEA 173 



Neptunus. 



Nephmus De Haan, A. Milne Ed- 

 wards, Miers. 

 AcJiclous, AiiipJiitrite Pontiis . De Haan. 



Arenceus Dana. 



Euctenota Gerstaicker. 



Hellemis A. Milne Edwards. 



Carapace nearly flat, with the dorsal surface granu- 

 lated, rarely tuberculated, usually marked with several 

 transverse lines, of which one is prolonged inwards for 

 a short distance from the lateral epibranchial spine. The 

 front projects but little, is divided into from five to eight 

 lobes or teeth, of which the two exterior constitute the 

 interior lobes of the orbits. The antero-lateral marfjins 

 are arcuated or nearly straight, and are divided into 

 eight nearly equal and well-developed teeth, including 

 the tooth or lobe at the exterior angle of the orbit, and 

 excluding the ninth or lateral epibranchial spine ; the 

 postero-lateral angles of the carapace are either rounded, 

 angular, or spiniferous. The orbits are widely open above ; 

 their superior margin is usually marked with fissures, and 

 sometimes dentated, and the infraocular lobe is produced 

 and dentiform or spiniform. The basal (or real second) 

 joint of the antennal peduncle is moderately dilated, and 

 barely reaches the frontal margin. The third joint of the 

 external maxillipedes is usually not at all produced at its 

 antero-internal angle. The endostome is longitudinally 

 ridged. 



The legs of the first pair are well developed, some- 

 times considerably elongated ; the fourth joint is armed 

 with spines on its anterior and sometimes on its posterior 

 margin. The fifth and palm are usually longitudinally 



