1GO A HISTORY OF RECENT CRUSTACEA 



which this genus and some of its immediate neighbours 

 are distinguished from one another. 



Pag arm (in restricted sense). The ' front ' without 

 distinct rostral projection. Eye-stalks stout, with basal 

 scales usually wide apart. Acicle of second antennas short 

 and robust, the flagellum long and naked. The third 

 maxillipeds approximate at the base. The left cheliped 

 usually the larger. The fourth pair of legs chelate. 



Eupagurus, Brandt, 1851. The 'front' with a dis- 

 tinct rostral projection. Eye-stalks stout, with basal 

 scales wide apart. Acicle of second antennas long and 

 slender, the flagellum long and naked. The third maxil- 

 lipeds distant at the base. The right cheliped usually the 

 larger. The fourth pair of legs subchelate. 



Olibanarius, Dana, 1852. The 'front' with a distinct 

 rostral projection. The eye-stalks usually slender, with 

 the basal scales close together. Acicle of second antennas 

 short, the flagellum naked. The chelipeds subequal and 

 similar. The fourth pair of legs chelate. 



Aniculus, Dana, 1852, and Galcinus, Dana, 1852, agree 

 with Olibanarius as above defined, except that Aniculus 

 has the fourth pair of legs subchelate, and Calcinus has 

 the chelipeds very unequal. 



Diogenes, Dana, 1852. There is a movable rostriforrn 

 process between the eye-stalks, distinct from the rostrum. 

 The acicle of the second antennas has a broad base ; the 

 flagellum is ciliated. The left cheliped is the larger. The 

 fourth pair of legs chelate. 



When characters are set out in this way, it would 

 seem that there should be little difficulty in determining 

 to what genus a species belongs, but nature does not 

 always lend itself very obligingly to the necessities of 

 classification. Thus, in regard to Pagurus similimanus, 

 Henderson, its author is obliged to say : ' The chelipedes 

 are of equal size, and in every respect similar to one 

 another, belonging essentially to the form which is charac- 

 teristic of the genus Clibanarius,' and presently afterwards, 

 under the species Clibanirius strigimdnus (White), Dr. 

 Henderson observes : ' As in the case of Pagurus simili- 



