Fig. 10. Coxal lamella of the penultimate pair of feet of the male (a), and coxal lamella, with the three following joints of the same pair of feet of the female (b) of Melita Messalina, magnified. Fig. 11. Coxal lamella of the same pair of feet of the female of M. insatiabilis. Fig. 10. Coxal lamella of the penultimate pair of feet of the male ( _a_ ), and coxal lamella, with the three following joints of the same pair of feet of the female ( _b_ ) of _Melita Messalina,_ magnified. Fig. 11. Coxal lamella of the same pair of feet of the female of _M. insatiabilis._ As the males of several species of Melita are distinguished by the powerful unpaired clasp-forceps, the females of some other species of the same genus are equally distinguished from all other Amphipoda by the circumstance that in them a peculiar apparatus is developed which facilitates their being held by the male. The coxal lamellæ of the penultimate pair of feet are produced into hook-like processes, of which the male lays hold with the hands of the first pair of feet. The two species in which I am acquainted with this structure are amongst the most salacious animals of their order, even females which are laden with eggs in all stages of development, not unfrequently have their males upon their backs. The two species are nearly allied to _Melita palmata_ Leach ( _Gammarus Dugesii,_ Edw.), which is widely distributed on the European coasts, and has been frequently investigated; unfortunately, however, I can find no information as to whether the females of this or any other European species possess a similar contrivance. In _M. exilii_ all the coxal lamellæ are of the ordinary formation. Nevertheless, be this as it will, whether they exist in two or in twenty species, the occurrence of these peculiar hook-like processes is certainly very limited.