

g7 g CRUSTACEA, 



Subtribb III. HYPERIDEA. 



The Hyperidea are oceanic species, and are mostly found remote 

 from the land. They seldom have the body much compressed, and 

 the epimerals are small. The variations they present have much 

 wider limits than among the Gammaridea. In the latter, the head is 

 almost identical throughout the groups, in general form as well as type; 

 while, in the Hyperidea, this segment takes many shapes, among the 

 species, and may even have a beak as long as the body. There is 

 also a much greater diversity among the legs than occurs in other 

 Amphipods. The five posterior pairs may be slender, and of the ordi- 

 nary unguiculate character, or hands of strange shapes may be deve- 

 loped on either of these pairs excepting the last ; or, again, the last 

 three pairs of legs may be obsolescent, except the basal joint, which is 

 extraordinarily enlarged, so as to become a kind of operculum for 

 covering the venter. The abdomen also has its modifications : for 

 besides the ordinary character, it possesses the power, in some species, 

 of folding itself up against the venter, and acting unitedly with the 

 operculiform basal joints of the three posterior pairs of legs, it closes 

 up the under surface of the body, making it like a box, with every 

 limb shut up within. The antennae have, too, their diversities. The 

 superior pair may be either obsolescent, or much elongated ; and the 

 inferior pair, although ordinarily extended in the usual manner, are 

 sometimes folded up, and thus concealed either side of the head. The 

 stylets are usually lamellar, and sometimes quite broad. ^ 



The large eyes are the most striking feature in the animals. They 

 may cover with facets the whole head, with, perhaps, only a narrow 

 medial line bare; and, in one genus, the rounded mass of pigment 

 makes one large eye within. In some of the Hyperidea, there appear 

 to be two spots of pigment, of different colour, either side of the 

 middle, as in the Arwhylomera purpurea, which has one mass of red, 

 and another of green (fig. 9, Plate 68), the former narrow and acumi- 

 nate below, the latter broad ovoidal. 



The Hyperidea are, therefore, those species among the Amphipoda, 

 in which nature indulges in her widest diversities of development, just 

 as with the Maioids and Leucosoids among the Brachyura; and, on 



