THE CANCROID CRx\.BS OF AMERICA 35 



F'. Chelipeds heavy, propodus dilated, its. lower margin 



convex asper, p. 56. 



F^. Chelipeds elongate, propodus not dilated, its lower 



margin straight or nearh' so panamensis, p. 58. 



D^.f Postero-distal margin of merus of swimming feet armed with a 

 row of spinules hut no spine. 

 E'. Frontal teeth blunt. Width of merus of swimming feet 



equal to length of anterior margin gibbesii, p. 49. 



E-. Frontal teeth sharp. Width of merus of swimming feet less 



than length of anterior margin xantusii, p. 50. 



B-. A stridulating ridge on lower surface of carapace. A spine at posterior 



'angle of carapace vocans, p. 60. 



A^. Carapace narrow; antero-lateral margin the arc of a circle with short radius, 

 whose center is near the center of the cardiac regior. 



Subgenus Achelous, p. 62. 

 B'. Carapace with posterior corners (marginal line) rounding, unarmed. 

 C*. Postero-distal margin of merus of swimming feet unarmed. Two 

 ■*$»- spines on upper margin of palm. 



D'. Lateral spine or tooth of carapace larger than the next tooth. 

 E^ Lateral spine of carapace similar to, and very little larger 

 than the next spine or tooth. Upper margin of movable 

 finger conspicuously fringed with long hair. 



depressifrons, p. 84. 

 E^. Lateral spine much larger than the next spine or tooth and 

 directed more outward. Hair on upper margin of mov- 

 able finger inconspicuous floridanus, p. 82. 



D-. Lateral tooth no larger than the preceding teeth. 



bahamensis, p. 90. 

 C^. Postero-distal margin of merus of swimming feet armed with one or 

 two spines or with spinules or with both. 

 D^ An erect spine on basis of swimming feet. A large round persis- 

 tent red spot on postero-lateral slope of carapace_sebae, p. 79. 

 D2. No erect spine on basis of swimming feet. No large persistent 

 red spot on postero-lateral slope of carapace. 

 E'. Postero-distal margin of merus of swimming feet armed with 

 one or two spines besides inconspicuous spinules. 

 F^ One spine at postero-distal angle of merus of swimming 

 feet. 

 G'. Frontal teeth sharp, spiniform. Lateral spine short. 

 H'. Merus of swimming feet as broad as long or 

 nearly so. Eight antero-lateral teeth equal, 

 spinimanus, p. 62. 

 H'. Merus of swimming feet half again as long as 

 broad. Antero-lateral teeth 2, 4 and 6 slightly 

 reduced. Carapace lumpy in the middle. 



stanfordi, p. 69. 



G^. Frontal teeth blunt-tipped. Antero-lateral teeth 



very unequal. Lateral tooth similar to and 



scarcely larger than seventh tooth _angustus, p. 70. 



F-. Two spines at postero-distal angle of merus of swimming 



feet; this merus distinctly longer than broad. 



brevimanus, p. 68. 

 E2. Postero-distal margin of merus of swimming feet armed with 

 spinules but no spines. 



