NCENIA TUBERCULOSA. 473 



armed, near the centre, with a broad double tubercle, 

 from which the animal derives its specific name ; the 

 finger is much curved, and not serrated upon the inner 

 margin. The walking legs are nearly of the same 

 length, and tolerably strong. The last pair of caudal 

 appendages terminate in a pair of styliform branches. 

 The central tail-piece is tubular, the oblique extremity 

 being furnished with a few minute denticles. 



We have taken this species, not unfrequently, with 

 the dredge off Plymouth, and in Oxwich Bay on the 

 south coast of Wales. Mr. Webster has also sent it to 

 us from Tenby, Mr. Edward from Banff, and Mr. Thom- 

 son procured it in Belfast Bay, Ireland. 



