THE HIPPOLYTIDJE 233 



other respects it agrees with Alphens, and the motive of its 

 name seems to be that as Beta stands close to Alpha in the 

 Greek alphabet, Betceus may be understood to stand close 

 to Alplieus in generic character. Betceus malleodigitus, 

 Spence Bate, from Fiji, has the finger of the first legs 

 shaped like a mallet, in that respect resembling Alplieus 

 malleator, Dana, and Alplieus obesimanus, Dana. Betceus 

 microstylus, Spence Bate, is distinguished with some doubt 

 from Betceus cequimanus, Dana. 



Family 3. Hippolijtidce. 



The rostrum is of important size; the eyes are not 

 covered by the carapace ; the mandibles may have a cutting 

 edge and ' palp,' or be without one or both. The first 

 pair of trunk-legs have moderate-sized chelas ; the second 

 pair are also chelate, with the wrist or fifth joint sometimes 

 much and sometimes little subdivided. 



A dozen or more genera are included in this family. 

 It is impossible here to do more than give an indication of 

 the complexity to which Spence Bate has afforded a clue 

 so far as his own views of the family are involved, but 



V } 



there is little agreement as yet as to the precise classifica- 

 tion of some of the genera concerned. 



The Challenger collection gave Spence Bate occasion 

 to deal with nine genera, seven of which were named or 

 established by himself. With these may be arranged 

 Caridion, a name substituted by Goes in 1863 for the pre- 

 occupied Doryphorus of Norman, and two genera that 

 were instituted in 1869 by G. 0. Sars, although in neither 

 of them is the rostrum quite up to the importance de- 

 manded by the character of the family. It must suffice 

 here to refer only to the mandibles and the second pair of 

 trunk-legs, using the word ' wrist,' for brevity's sake, 

 instead of saying in full the fifth joint of the second pair 

 of trunk-legs. 



Plaiybema, Spence Bate, 1888. Mandibles without 

 cutting edge or ' palp.' Wrist two-jointed. 



Caridion, Goes, 1863. Mandible with cutting edge 

 and three-jointed 'palp.' Wrist two-jointed. 



