128 BULLETIN 97, UNITED STATES NATIONAL MUSEUM. 



KEY TO THE AMERICAN GENEKA OF THE SUBFAMILY PINXOTHERELIIXAE. 







A*. Last joint of outer maxilllped articulated near proximal end of inner side 



of penultimate joint. 



B 1 . Carapace much wider than long. Third leg longest. 

 G 1 . Third leg much longer than fifth. Lower or true antero-lateral margin 



forming an angle with postero-lateral margin Pinuixa, p. 128. 



C*. Legs varying little in length. Lower or true qntero-lateral margin 



curving gradually into postero-lateral margin Sclcroplax. p. 170. 



B*. Carapace very little wider than long. Second and third legs nearly equal. 



C 1 . Ischiura of outer maxilliped well defined Opisthopus,p. 172. 



C s . Ischium of outer maxilliped either fused with merus, or only partly 



so Pinnaxodcs, p. 174. 



A*. Last joint of outer maxilliped articulated at distal end of penultimate joint 



Second leg longest. 



B*. Proximal end of last joint of outer maxilliped narrow, distal end of pe- 

 nultimate joint wide. Carapace uneven. Spinules on chelipeds and 



legs Tctrias, p. 179. 



B". Proximal end of last joint of outer maxilliped same width as distal end 

 of penultimate joint. Carapace smooth. No spiuules on chelipeds or 

 legs Pinnotherelia, p. ISO. 



Genus PINNIXA White. 



Plnnixa WHITE, Ann. Mag. Nat. Hist., vol. 18, 1846, p. 177 ; type, P. cylin- 

 drica White. RATHBUN, Bull. U. S. Fish Comm., vol. 20, for 1900, 

 pt. 2 (1901), p. 21. 



TuUcola LOCIUNGTON, Proc. California Acad. Sci., vol. 7, 187G (1877), p. 

 55 [1] ; type, T. longipcs Lockiugton. 



Carapace much wider than long; integument usually firm. Front 

 narrow, nearly transverse, with a median groove. Orbit broadly 

 ovate or nearly circular, with a wide inner hiatus, which is partly 

 occupied by the basal antennal joint. Antennules transversely or 

 obliquely plicated in wide fossettes which communicate with each 

 other beneath the front. Eye-stalks very short. Epistome linear- 

 transverse. Ischium of maxillipeds small, merus large, distal por- 

 tion of outer margin convex; palp jointed to summit of merus; third 

 joint articulated on inner side of the preceding one near base. 



Chelipeds of moderate size; merus trigonous; carpus usually 

 smooth ; hand large, compressed. Second ambulatory leg larger than 

 first ; third largest of all ; fourth much shorter than third and rela- 

 tively stouter than first and second. Abdomen in both sexes usually 

 7-jointed and narrower at base than width of last sternal segment. 



Uabitat. Live in bivalve mollusks, in tubes or holes of worms, in 

 wormlike holothurians, and in mud. 



The genus occurs in Japan and Australia as well as in America. 



