No. 403.] MWORTH-AMERICAN INVERTEBRATES. 587 
D. External maxillipeds with a wide rhomboidal gape 
Pachygrapsus 
D’. External maxillipeds with a narrow gape Hemigrapsus 
B'. External maxillipeds with a piliferous ridge . . . . Sesarma 
A. Antenne visible from above... 9. ose NE or ee 
THE SPECIES OF GRAPSID;E.! 
Genus Planes Leach 
` P. minutus (Linneus), MSAPD, at surface, on floating weed 
Genus Pachygrapsus Randall. 
Key to Species, 
A. Lateral margins strongly arcuate P. crassipes Randall, PD 
A’. Lateral margins converging posteriorly from the lateral tooth 
P. transversus Gibbes, M?G D’ 
Fic. 6. — Cardisoma guanhumi Fic. 7.— Cardisoma guanhumi, outer maxilliped. 
Genus Hemigrapsus Dana. 
Key to Species. 
A. Front with a deep sinus at the middle XH. oregonensis (Dana), APD 
A’. Front arcuate, very slightly sinuous. . . Z7. nudus (Dana), APD 
Genus Sesarma Say. : 
Key to Species. 
4. Lateral margin toothed behind the orbital angle 
S. (Sesarma) reticulatum Say, MSG 
A’. Lateral margin entire. . S. (Holometopus) cinereum (Bosc), MSG 
Genus Plagusia Latreille De ee P depressa (Fabricius), S 
! Grapsus grapsus (Linnaeus), a tropical species, has been taken at Cape Cod 
from the bottom of a whaler just returned from a voyage. 
? Occasional. 3 California (Kingsley). 
