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. 
