548 PHILOSOPHY OF ZOOLOGY. 



2. CoRYSTEs. 3. Thia. 4. Atelecylus. 

 Subdivision 2. Antennae moderate, simple. Hinder 

 pair of legs with compressed claws. 



5. PORTUMNUS. 6. CaRCTNUS. 7. PORTUNUS. 8. 

 LUPA. 



Subdivision 3. Antennae moderate, simple. Four hinder 

 pair of legs compressed. 



9. Mantua. 



Subdivision 4. Antennae simple, short. Four hinder 

 pair of legs simple. 



10. Cancer. 11. Xantho. 12. Calappa. 



B. Abdomen in both sexes seven jointed. Two anterior 

 legs dedactyle. 



Division I. Eight hinder legs simple, and alike in 

 form. 



Subdivision 1. Shell anteriorly arcuated, the sides con- 

 verging to an angle. Two anterior legs unequal. 



13. PiLUMNus. 14. Gegarcinus. 



Subdivision 2. Shell quadrate, or subquadrate. Eyes 

 inserted in the front. 



• Shell quadrate. Eyes with a short peduncle. 



15. PiNNOTERES. 



** Shell quadrate. Eyes with a long peduncle. 



16. OCYPODE. 17. UCA. 18. GONOPLAX. 



Subdivision 3. Shell quadrate. Eyes inserted at the 

 anterior angles of the shell. 



19. Grapsus. 



Division II. Two hinder legs at least dorsal. 

 Subdivision 1. Two posterior legs dorsal. Eyes with 

 the first joint of the peduncle elongated. 



20. HOMOLA. 



Subdivision 2. Four hinder legs dorsal. Eyes with 

 the first joint of the peduncle short. 



21. DoRippE. 22. Dromia. 



