MYSIS CHAMELEON. 337 



becomes a little narrowed forwards, is obliquely truncate at 

 the apex, with a small tooth on the outer angle, and it is 

 ciliated with rather long hairs on the inner side and at its 

 extremity. The middle plate of the tail is bifurcate at the 

 apex, longitudinally grooved on each side of the median 

 line, minutely toothed on the sides, and with a stronger 

 tooth on each apex. The lateral laminae are ciliated on all 

 sides with long hairs ; the inner is long-lanceolate, and 

 acute ; the outer is longer, and rounded at the extremity. 



It often reaches the length of an inch and a quarter. 



" Nothing," says Mr. Vaughan Thompson, " can shew 

 the fallacy of colour in distinguishing the species, more 

 clearly than the variety of tints which Mysis chameleon 

 assumes, as it occurs here in the river Lee and the harbour 

 of Cove, and which have suggested its trivial name ; in 

 the upper part of the river, below the city of Cork, it 

 occurs of different shades of grey, inclining at times to 

 black, having invariably the greater part of the anterior 

 scales, inner branch of the inferior antennae and joints of 

 the outer laminae of the tail, black, and the fringe of the 

 scales tinged with pink ; lower down amongst the littoral 

 fuci, it takes various tints of brown ; and those obtained 

 from sites abounding in Zostera and Ulvae, present us with 

 green colours of greater or less intensity." 



I have quoted the above account of the variation of 

 colour in this species in the author's words, in order to 

 shew that difference of colour alone can afford no ground 

 for considering this species as distinct from the spinulosus 

 of Leach. And yet Mr. Vaughan Thompson, in his de- 

 scription of the latter (which he names M. Leachii), gives 

 colour as the only tangible distinction. I am decidedly 

 of opinion that they constitute but one species, and I have 

 retained the name of cham&leon, as spinulosus is equally 

 applicable to various other species of the genus. 



