254 HISTORY OF BRITISH CRUSTACEA. 



body, are confused together, the thorax is very wide, and 

 the eyes cease to be visible. 



Fam. IONIDjE. 



Abdominal appendages filiform and surrounding the ab- 

 domen. 



Gen. 133. IONE. 



Body, in the female, pyriform and very flat, in the male, 

 narrow and elongated ; the abdomen of six segments, each 

 bearing a pair of membranous, cylindrical, slender, very 

 long appendages; in the female the appendages, fixed to the 

 five first segments, are very long and arborescent. The head 

 of the male has two pairs of antennae. 



Ione thoracica, Montagu, sp. (Plate XIY. fig. 8.) — 

 Colour generally orange, appendages whitish ; male much 

 more slender, and without cirri on front of the body. 



Colonel Montagu remarks, "This curious species inhabits 

 the thoracic plate of CaUianassa subterranea, concealing 

 itself between the fleshy part and the shell, and forming a 

 tumour on one side. From this situation I have extracted 

 it alive, and have kept it in that state for several days in a 

 glass of sea-water/' In the few specimens observed by 



