258 GA.MMARID.E. 



A MPHIP ODA . GAMMA RIDES. 



NATATORIA. 



Genus CALLIOPE. 



Calliope. LEACH, MS. Coll. Brit. Mus. SPENCE BATE, Cat. Amph. Brit. 

 Mus. p. 148. WHITE, Hist. Brit. Crust, p. 179. 



Generic character. Like Pherusa, except that at least the 

 second pair of gnathopoda have the propodos largely developed. 



THIS genus, like the preceding, partakes, in a strong 

 degree, of the more or less arbitrary character of the 

 majority of generic divisions, differing from Pherusa 

 in nothing but the relative proportions of one or 

 both of the first two pairs of legs. Although to a cer- 

 tain extent the separation is not natural, we con- 

 sider that it will be found convenient to adopt Leach's 

 views in distinguishing the large-handed species from 

 those in which the hands are uniformly very slender and 

 feeble. Paramphithoe of Bruzelius (Acanthosoma, Owen) 

 and Amphithonotus of Costa, have no stronger claims 

 to generic distinction than Atylus, Pherusa, and Calliope, 

 and by sinking them, we should link together in one 

 genus some widely different forms, and so fall into a 

 similar error with Costa and Stimpson, the former of 

 whom united Dexamine spinosa (Amphitoe Marionis, Milne 

 Edwards), Pleustes panopla (Amphitoe panopla, Kroyer), 

 and Atylus carinatus (Gammarus carinatus, Fabricius), and 

 the latter also added Paramphithoe hystrix (Acanthosoma 

 hystrix, Owen) in one genus under the name of Amphi- 

 thonotus. 



