LYSIANASSA AUDOUTNIANA. 81 



oblong-ovate, and have the posterior margin simple. 

 The caudal appendages are simple : the antepenultimate 

 pair have the branches styliform, naked, slightly curved, 

 and tipped with a rudimentary spine ; the penultimate 

 resemble the preceding, except that the posterior margin 

 of each branch has its distal moiety minutely serrated. 

 The ultimate pair have the base very short, and one 

 branch simple, the other two-jointed and tipped with a 

 minute spine ; the inner margin of the single-jointed 

 branch, and the first joint of the double-jointed one, are 

 minutely serrated. The central tail-piece is simple, 

 squamiform, concave above, and rounded at the apex. 



The animal is of a dull yellow colour, darkest along 

 the course of the alimentary canal. 



This species has been taken by us, in Plymouth Sound, 

 with a dredge ; but we have not noticed it among those 

 Crustacea sent to us by our many obliging correspond- 

 ents from other localities. 



The species is named in honour of M. Audouin, the 

 able coadjutor of M. Milne-Edwards, and who, as the 

 describer of the Amphipoda in Savigny's *' Egypt," must 

 be reckoned among the pioneers of this branch of Car- 

 cinology. 



