io8 



Pterygostomian regions and side of carapace not presenting 

 reticulating lines 5 



2. Antennae entering the orbits 3 



Antennae excluded from the orbit; if the inner suborbital 



lobe does not meet the front, the postfrontal lobes are 

 scarcely. separated one from another 4 



3. Front nearly always sharply deflexed; carapace flattened, 



often covered with numerous tufts of hairs .... Sesarma Say 

 Front obliquely deflexed, postfrontal lobes rounded ante- 



riorly; carapace vaulted, naked Sarmatium Dana 



4. Carapace naked, with subregions scarcely indicated ; antero- 



lateral margins not toothed Metasesarma H. Milne-Edwards 



Carapace covered with a short fur-, antero-lateral margins 



twice emarginated behind external orbital angle . . . Clistócoeloma A. Milne-Edwards 



5. Distance between external orbital angles decidedly ex- 



ceeding length of carapace; antero-lateral margins with 

 two distinct teeth behind external orbital angle. Eye- 

 stalks rather long, about as long as the width of 

 the front, which latter rapidly narrows anteriorly. Sub- 

 orbital crest in c? divided into obtuse lobules and 

 extending far behind the orbit. Ambulatory legs long 



and slender Metaplax H. Milne-Edwards 



Distance between external orbital angles not much ex- 

 ceeding length of carapace ; antero-lateral margins entire 

 or toothed. Eye-stalks much shorter than the width of 

 the front. Ambulatory legs not particularly slender. . 6 



6. Lateral margins of carapace arched, very feebly toothed 



or entire Cyclograpsus H. Milne-Edwards 



Lateral margins of carapace always distinctly toothed. . 7 



7. Width of fronth between eye-stalks much less than half 



the distance between external orbital angles, with the 

 anterior margin passing imperceptibly into the much 

 oblique inner margins of the orbits. Abdomen of d" 



broadest at 3 d segment 8 



Width of front half the distance between external orbital 

 angles, with the lateral angles of the anterior margin 

 distinct. Abdomen of cf regularly tapering from base 

 to tip Paragrapsus H. Milne-Edwards 



8. Lateral margins of carapace much convex in their entire 



course Chasmagnathus de Haan 



Lateral margins of carapace subparallel in posterior half Hehce de Haan 



108 



