234 A HISTORY OF RECENT CRUSTACEA 



Latreutes, Stimpson, 1860. Mandibles without cutting- 

 edge or ' palp.' Wrist three-jointed. 



Hippolyte, Leach, 1813. Mandible with cutting edge, 

 without ' palp.' Wrist three-jointed. 



Cryptocheles, Sars, 1869. Mandible with cutting edge, 

 without ' palp.' Wrist seven-jointed. 



Bythocdris, Sars, 1869. Mandible with cutting edge, 

 without ' palp.' Wrist nine-jointed. 



Spirontocdris, Spence Bate, 1888. Mandible with 

 rudimentary cutting edge, and ' palp.' Wrist 

 seven-jointed. 



Nauticdris, Spence Bate, 1888. Mandible without 

 cutting edge, with three-jointed ' palp.' Wrist 

 seven-joint ed. 



[Hetaints], Spence Bate, 1888. Mandible with cutting- 

 edge and two-jointed ' palp.' Wrist seven-jointed. 



Merliippolyte, Spence Bate, 1888. Mandible with 

 cutting edge and three-jointed ' palp.' Wrist 

 many-jointed. 



Chorismus, Speuce Bate, 1888. Mandible with rudi- 

 mentary cutting edge and three-jointed ' palp.' 

 Wrist many-jointed. 



AmpMplectus, Spence Bate, 1888. Mandible with 

 cutting edge and two-jointed ' palp.' Wrist 

 many-jointed. 



Of these genera the first is not new but newly named, 

 having been originally called Cydorliynclius by de Haan, 

 and then Rhynchocyclus by Stimpson, in allusion to the 

 laterally compressed, deep, and terminally orbiculate 

 rostrum. Unfortunately both names were preoccupied. 

 The new name literally means a broad platform, but was 

 evidently given under the impression that, as in English 

 the word rostrum may stand either for a beak or a plat- 

 form, so the Greek word for a platform might equally well 

 stand for a beak, which is not exactly the case. The dis- 

 tinctions between this genus and Latreutes reach almost a 

 vanishing point, when it is observed that both Stimpson 

 and de Haan give to the type species Platylema planirostris 



