348 A HISTORY OF EECENT CKUSTACEA 



the ^gidae Lave the flagella of both pairs of antennas 

 markedly distinct from the peduncles, and the earlier 

 pleopods, the uropods, and the terminal segment of the 

 pleon ciliated. 



^ga, Leach, 1815. The maxillipeds have seven joints, 

 or at the least six. In the female with eggs, the first pair 

 of marsupial plates are so large that they cover up all the 

 parts of the mouth except the clypeus, part of the upper 

 lip, and about half the ' palp ' of the mandible, thus leaving 

 the animal incapable of taking food. In accordance with 

 this condition, the ovigerous female, it is said, has never 

 been taken upon a fish. 



Rocinela, Leach, 1818. The maxillipeds are four- 

 jointed ; the mandibles have the apex narrow, not denticu- 

 late, and the second joint of the ' palp' not much longer 

 than the first. 



Alitropus, Milne-Edwards, 1840. The maxillipeds are 

 four-jointed. It is doubtful whether this genus should be 

 separated from Rocinela. The descriptions of AUtropus 

 iypus, Milne-Edwards, and of AUtropus foveolatus, Schiodte 

 and Meinert, do not supply characters for discriminat- 

 ing it. 



Syftcenus, Harger, 1878. The maxillipeds are four- 

 jointed. The mandibles have the apex flattened and denti- 

 culate, and the second joint of the ' palp ' shorter than the 

 first. The type-species, Syscenus infelix, Harger, is with- 

 out eyes. 



In the ' British Sessile-eyed Crustacea,' Bate and West- 

 wood describe four species of JEga. The first is called ^ga 

 bisarinata, Leach, which must yield to the earlier name 

 j3^ga rosacea (Risso), a Mediterranean species, for the 

 occurrence of which in Great Britain there is no definite 

 authority. It is very like ^^ga Stromii, Liitken, but dis- 

 tinguished from it by much smaller and more widely 

 separated eyes. It is now known that the specimen men- 

 tioned by the above-named authors as sent them by the 

 Rev. A. M. Noi-man from the coast of the county of Durham, 

 was in fact an ^^ga Stromii with eyes contiguous. The 

 second species ^ga tridens, Leach, has also large eyes, 



