PEREIONGTUS. 
221 
author in the “ Magasin de Zoologie 5 ’ for 1836. Of this 
latter genus we have had the opportunity of examining 
only a single specimen of P. Rissoanus , taken by Mr. J. 
Gwynn Jeffreys on the shores of Piedmont, but the 
specimen being small, we were not able to make out 
the form of the last pair of caudal appendages without 
dissection, and we felt unwilling to destroy our only 
specimen. We are therefore led to infer either that 
Guerin’s description of the posterior pair of caudal 
appendages is incorrect, or that Montagu’s specimen 
belongs to a distinct but closely-allied genus ; and pre- 
fer to adopt a new generic name, rather than to assume, 
without further evidence, that so accurate an observer as 
M. Guerin-Meneville can have been mistaken. 
The accompanying vignette is a scene off Flamborough 
Head. 
