234 A HISTOKY OF EECENT CKUSTACEA 



Latreutes^ Stimpson, 1860. Mandibles without cutting 



edge or ' palp.' Wrist three-jointed. 

 Hippolyte, Leach, 1813. Mandible with cutting edge, 



without ' palp.' Wrist three-jointed. 

 CryptocJieles, Sars, 1869. Mandible with cutting edge, 



without ' palp.' Wrist seven-jointed. 

 Bythomris^ Sars, 1869. Mandible with cutting edge, 



without ' palp.' Wrist nine-jointed, 

 Sjnrojitocdris, 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-jointed. 

 \_TIetairus']^ Spence Bate, 1888. Mandible with cutting 



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

 Merhippolyte, Spence Bate, 1888. Mandible with 



cutting edge and three-jointed ^ palp.' Wrist 



many-jointed. 

 Chorismus, Spence Bate, 1888. Mandible with rudi- 

 mentary cutting edge and three-jointed ' palp.' 



Wrist many-jointed. 

 AmphipJedus, 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 Gyclorhynchus by de Haan, 

 and then Ehynchocydus 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 jilat- 

 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 s])ecies Piatyhema planirosiris 



