of the Pontoniidse. 391 



Alpheus Edwardsii, Couch, Proc. Linn. Soc, Zool. v. p. 210 (1860). 

 Pontonella glabra, Heller, Crust, s'udl. Eur. p. 254, pi. viii. tigs. 12-17 

 (1863). 



Mediterranean ; Cornwall. 



Key to the Genera of Pontoniidai. 



I. Scale of second antenna not rudimentary. 



A. Antepenultimate joint of third maxilliped 



never more than moderately hroad. Last 

 two joints not contrasting sharply in 

 breadth with the antepenultimate. 



1. Dactyles of last three pairs of legs without 



basal protuberance. Last two joints of 

 third maxilliped narrow. 



a. Dactyles of last three pairs of legs 



straight. Rostrum almost always 

 with dorsal dentate crest, not bent 

 downwards, not with abrupt or 

 rounded end Periclimenes, Costa, 



b. Dactyles of last three pairs of legs [1844. 



curved. Rostrum without dentate 

 dorsal crest, bent downwards, with 

 abruptly pointed or rounded end .... Anchistus, gen. nov. 



2. Dactyles of the last three pairs of legs 



with basal protuberance. Last two 



joints of third maxilliped broad Coralliocaris, Stimp- 



B. Antepenultimate joint of third maxilliped [son, 18.00. 



broad. Last two joints usually contrasting 

 sharply in breadth with the antepenulti- 

 mate. 



1. Last two joints of third maxilliped to- 



gether longer than the preceding joint. 

 Last joint of second maxilliped borne 

 laterally by the penultimate joint Harpilius, Dana, 1852. 



2. Last two joints of third maxilliped 



together shorter than the preceding joint. 

 Last joint of second maxilliped borne 

 terminally by the penultimate. 



a. Dactyles of last three pairs of legs 



curved, with a low basal prominence. 

 Flagellum of second antenna short. 

 Last two joints of third maxilliped 

 fairly broad Conchodytes, Peters, 



b. Dactyles of last three pairs of legs [1851. 



straight, without basal prominence. 

 Flagellum of second antenna not 

 short. Last two joints of third 



maxilliped narrow Pontonia, Latreille, 



[1829. 



II. Scale of second antenna rudimentary Typton, Costa, 1844. 



9 7* 



