SYSTEMATIC ACCOUNT 185 



propodus. The third and fourth thoracic appendages (Text-fig. 216) are both alike, and are directed 

 forwards and curved towards the mouth ; each is about one and a half times the length of the second 

 thoracic appendage and is considerably stouter. The inner margins of the merus, carpus and propodus 

 bear long setae ; the dactylus ends in a curved claw. The remaining four pairs of thoracic appendages 

 are all very similar; they are stout and ambulatory in function (Text-fig. 21c) and the dactylus of 



Text-fig. 19. Xenarcturus spinulosus g.n., sp.n. (a) Head and first pereion (second thoracic) somite, x 12. 



(b) Dorsal view of pleotelson. x 7. 



Text-fig. 20. Xenarcturus spinulosus g.n., sp.n. (a) Antennule, x 32. (6) Antenna, x 32. (c) Left mandible (dorsal view), x 50. 

 {d) Right mandible (ventral view), x 50. (e) Right maxilliped (ventral view), x 50. (/) Left maxillula, x 60. (g) Left maxilla, 

 X 60. 



each ends in a curved claw. The distal end of the merus of the last thoracic appendage has its inner 

 angle produced to form a subacute projection. The surface of the joints is covered with scattered 

 spinules similar to those covering the body surface. 



In the breeding female, brood lamellae are developed on each of the second to the fifth pairs of 

 thoracic appendages inclusive. 



The first pleopod of the male (Text-fig. 22b) has the exopod modified as a copulatory organ; it is 

 longer than the endopod and has its distal portion bent almost at right angles and drawn out into an 

 acute point. Its outer concave margin bears a number of plumose setae ; a similar modification is seen 



