REPORT ON THE AMPHIPODA. 1005 



" Lower Lip with very broad plates ; the inner plates large. 



" First Maxillse armed with strong spines, some furcate some serrate ; the palp 

 large, two-jointed ; the palp of the left maxilla apically armed with spines, that of the 

 right with teeth ; the inner plate more or less strong. 



" Maxillipeds with the outer plate larger or smaller, but never very large, armed 

 on the margin with teeth (rarely spines) and apically with curved setae ; the inner plate 

 elongate, furnished with three teeth and many setae ; the palp elongate ; the last joint 

 towards the apex very narrow, unguiform. 



" The body more or less compressed. 



" The four anterior [pairs of] side-plates generally of moderate size, rarely small. 



" Antennas elongate ; the Upper with a multi-articulate flagellum and an accessory 

 flagellum ; the Lower only with a short flagellum. 



" First and Second Gno.thopods with the hand subcheliform. 



" The Fourth Peraeopods a little longer (paulatim crescentes) than the Third, the 

 Fifth than the Fourth. 



" Uropods biramous ; very rarely the last pair uniramous (simplices). 



" Telson laminar, cleft or not cleft." 



In regard to the mandibles it should be noticed that as a rule the inner plate of 

 the right mandible differs from that of the left ; it may be questioned whether Boeck's 

 distinction between the armature of the palp on the left and that on the right in the 

 first pair of maxillae is of general application ; in regard to the comparative length of 

 the hinder peraeopods there is an exception to Boeck's rule, by his own account, in 

 Garnmaracanthus loricatus, Sabine, of which he says that the fifth peraeopods are 

 shorter than the preceding ; lastly, with respect to the uropods, it will be found that he 

 does not describe any of his genera as having the third pair uniramous, although in 

 Melita the inner branch is very small (minimo), and little (parvulo) in Niphargus. 



For the earliest definition of the " Gammarinae " as a family, see Note on Latreille, 

 1802 (p. 72). 



For the earliest definition of the family " Gammaridae," see Note on Leach, 1814 

 (p. 86) ; Leach places in it the genera Melita, M&ra, Gammarus, Ampithoe, Pherusa, 

 the first three of which are still retained in the family. 



Genus Gammarus, J. C. Fabricius, 1775. 



1775. Gammarus, Fabricius, Systema Entomologies, No. 129. 

 1777. „ Fabricius, Genera Insectorum, p. 142. 



1779. „ Fabricius, Reise nach Norwegen, p. 258. 



1781. „ Fabricius, Species Insectorum, p. 515. 



1787. „ Fabricius, Mantissa Insectorum. 



1788. Cancer Gammarus, Gmelin's Caroli a Linne Systema Naturae, Tom. i. pars v. p. 2991. 



