AMPHIPODA. 279 
female., these segments carry beneath them plates, forming sacs, for the eggs. The 
second, fifth, sixth, and seventh segments are provided with short limbs, termin¬ 
ating in a sharp, pointed segment, which closes against the 
enlarged penultimate segment as the blade of a pocket- 
knife closes on its handle. By means of these chelate 
appendages the animals fasten themselves to the skin of 
cetaceans, thrusting their sharp claws into the epidermis, 
and adhering so firmly as to be able to withstand the dash 
of the waves. 
The members of the tribe Hyperina differ from the 
last by the larger size of the head, the more prominent eyes, 
and the absence of a palp on the maxillipedes. To this 
tribe belongs the large Cystosoma, a pelagic animal, probably 
retiring during the day to a considerable depth, but occasion¬ 
ally coming to the surface. The animal is colourless and transparent, so that by 
transmitted light the internal organs can be seen. The head is large and inflated, 
with its upper surface occupied by two enormous eyes. The genus Phronima also 
contains species attaining a considerable size, examples of the European P. sedentaria 
transparent ocean-shrimp, Cystosoma nejotuni (reduced). 
whale-louse, Cyamus 
(nat. size). 
