Order DECAPODA 



Suborder Reptantia 



Tribe BRACHYURA 



KEY TO SUBTRIBES OP THE TRIBE BRACHYURA 



\K Anterior thoracic sterna very broad, posterior thoracic sterna 

 narrow and keel-like. Posterior thoracic epimera largely 



exposed by reduction of the branchiostegite GYMNOPLEUBA (p. 6) 



A^. Anterior thoracic sterna not unusually broad, posterior thoracic 



sterna not keel-like. Posterior thoracic epimera covered by 



branchiostegite. 



B\ Mouth field (endostome) prolonged forward to form a gutter. 



Last pair of legs normal or abnormal. Female openings 



generally sternal. First abdominal limbs lacking in female. 



Gills few OXYSTOMATA (p. 75) 



B2. Mouth field roughly square. 



C. Buccal cavity covered by the external maxillipeds or 

 nearly so. 

 D'. Last pair of legs abnormal, dorsal. Female openings 

 coxal. First abdominal limbs of female present. 



Gills usually many DROMIACEA (p. 27) 



D^. Last pair of legs normal, rarely reduced or dorsal. 

 Female openings sternal. First abdominal limbs 



of female lacking. Gillsfew BBACHYGNATHA Mp- 264) 



C^. Buccal cavity very wide, not covered by the narrow 



external maxillipeds HAPALOCABCINIDEA (p. 258) 



Subtribe Gymnopleura Bourne 



Gymnopleura Bourne, Journ. Linn. Soc. London, Zool., vol. 35, p. 55, 1922. 



Anterior thoracic sterna broad, posterior thoracic sterna narrow 

 and keel-like; posterior thoracic epimera largely exposed by reduction 

 of branchiostegite; female openings on coxae; last pair of pereiopods 

 dorsal in position, normal or reduced in size; sternal canal present; 

 thoracic nerve ganglion-chain elongate; antennary sternum triangular, 

 spout-shaped ; branchiae eight on each side. (Bourne.) 



Family RAN IN ID AE Dana 



Raninidae Dana, United States Exploring Expedition, Crustacea, pt. 1, p. 390, 

 1852; pt. 2, p. 1428, 1853. — Henderson, Voyage of H. M. S. Challenger, 

 Anomura, vol. 27, p. 27 (characters on p. 26), 1888. — Alcock, Journ. 

 Asiatic Soc. Bengal, vol. 65, p. 288, 1896. — Bourne, Journ. Linn. Soc. 

 London, Zool., vol. 35, p. 56 et seq., 1922. 



2 In this buMetin the geous Geryon only, family Goneplacidae. 

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