1880.] NATURAL SCIENCES OF PHILADELPHIA. 189 



Meros of external maxillipeds broader than long. 



Meros as long as ischium. Glyptogra'psus. 



Meros shorter than ischium. Utica. 



Meros as long or longer than broad. 



Front nearly half as wide as carapax. Heterograpsus. 

 Front not over one-third as wide as carapax. Eriocheir. 

 Palpus articulating with the outer angle of the meros of the ex- 

 ternal maxilliped. 



One tooth behind the orbital angle. Perig7'(ipsus. 



More than one tooth behind the orbital angle. Platygrapsvs. 

 External maxillipeds with an oblique piliferous ridge. Sesarmini. 



Meros of external maxilliped elongate, its apex rounded. 

 Antennae excluded from the orbit. Metasesdrma. 



Antennae not excluded from the orbit. 

 Carapax subquadrate, sides ai'cuate. 

 Joints of ambulatoiy feet entire. Sarmatium. 



Joints of ambulatory feet dentate. Bhaconotus. 



Carapax quadrate, sides straight. Sesarma. 



Carapax elongate, narrowed behind. Aratus. 



Mei'os of external maxilliped short, its distal border truncate or even 

 excavate, and bearing the palpus. 



Antennae excluded from the orbit. Clistocoeloma. 



Antennae entering the orbit. 



Sides of carapax straight. Helice. 



Sides arcuate. 



Sides entire. Cyclograpsns. 



Sides emarginate or toothed. Chasmagnathus. 



Antennae lodged in notches in the front, and visible from above. 



PLAGUSm^. 

 Meros of external maxillipeds large, as broad as ischium. Plagi/sia. 



Meros small and much narrower than ischium. Leiolophus. 



Sub-family Grapsinse {Grapsinm et Sesarmince Dana). 

 Antennulse more or less transverse, and covered by the front. 



Tribe GRAPSINI (Sub-family Grapsinse Dana). 



§ External maxillipeds -without an oblique piliferous ridge on 

 the ischial and meral joints. 



Genus GONIOPSIS De Haan, 1835 (Goniograpsus (pars) Dana, 1851). 



Carapax flat ; front vertical, over half as wide as carapax ; 

 sides straight, one-toothed. Suborbital lobe broad, reaching the 

 front and excluding the antenna from the orbit. External max- 

 illipeds slender ; meral and ischial joints of equal length. 



