NO. 1199. CRUSTACEANS OF WEST AFRICA— BATHBUN. ' 273 



F'. Basal joint of antenn;© very small, and with the next joint embedded 

 in the narrow gap between the front aud the inner orbital 



angle Family PAKTHP^NOPiDiE. 



C. Buccal frame usuallj' triangular, narrowed forward. Efferent channels 

 opening at middle of endostome. Male genital openings on the 



basal joint oi" the last pair of legs Tribe Oxystomata. 



D. Last one or two pairs of feet not articulated higher np than the preceding 

 pairs. 

 E. Afferent channels to the branchi;e opening behind the pterygostomian 

 regions and in front of the chelipeds. 

 F. Fifth and following joints of the third maxillipeds not wholly con- 

 cealed by the fourth joint P^amily calappid/e. 



F'. Fifth and following joints of the third maxillipeds concealed behind 



the triangular acute fourth joint Family matutidje. 



E'. Afferent channels to the branchite not in front of bases of chelipeds, but 

 at the antero-lateral angles of the endostome. 



Family leucosiid^. 

 D'. Last one or two pairs of feet articulated higher up than the preceding 

 pairs. 

 E. Afferent channels to the branchiaj in front of bases of chelipeds. 



Family dorippid^. 

 E'. Afferent channels to the branchiae not in front of bases of chelipeds. 

 Pleon short, not folded under the carapace. 



Family RANiNiDiE. 



B'. Branchite more than nine Tribe Anomala. 



C. Last one or two pairs of feet subdorsal, often prehensile, for carrying a shell, 

 sponge, or leaf over the body as a means of concealment. 



Family dromid.e, 



A'. Body elongate, with the abdomen or pleon usually well developed, longer than 



the carapace, and extended, or partially so, never closely redexed 



against the sternum Suborder MACEURA_ 



B. Body not compressed. Eostrum depressed, often wanting. First abdominal 

 segment shorter and narrower than the following. Abdominal 

 appendages not oar-shaped. The articulation between the car- 

 pus and propodus at two fixed points. 

 C. Abdomen with hard integument, tapering, and recurved from the middle, aud 

 without a swimming fan. Second to fifth pairs of legs short 

 and wide, with terminal joint wide, curved oiitwardly for swim- 

 ming and digging in the sand Tribe Hippidea. 



Family hippid^e. 

 C. Abdomen sometimes soft; when hard it is usually provided with a swimming 

 fan. Second to fifth pairs of legs not wide nor with terminal 

 joint flattened and curved for swimming and digging. 

 D. Abdomen or pleon usually soft and membranaceous and spirally twisted. 

 Carapace weak or membranaceous behind the cervical groove. 

 Chelipeds and two following pairs of legs well developed, the 

 last two pairs small, one or both being usually chelate. 



Tribe Paguridea. 



E. First antenna^, with peduncle elongate, first joint as long as eyestalks. 



Second antennte with peduncle compressed. Hermit crabs 



chiefly Family ccenobitid^. 



E'. First antennai with peduncle of moderate size, first joint short and stout. 

 Second antennte with peduncle subcylindrical. Hermit crabs. 



Family pagurid^. 

 D'. Abdomen or pleon with firm integument. Carapace not weak behind the 

 cervical groove. 

 Proc. jST, M. vol. xxii 18 



