308 



It may perhaps appear, without a careful comparison of 

 numerous specimens of both species, that the characters 

 above named are scarcely sufficient to warrant their se- 

 paration ; but it happens that an additional distinctive 

 character obtains invariably, associated with the different 

 number of the rostral teeth. The rostrum in the present 

 species is covered with innumerable reddish dots, which 

 continue to be very visible from their opacity, even after 

 all colour has been removed from long immersion in spirit. 

 In P. Squilla there are no such coloured dots. 



I have given to this species the name of my lamented 

 friend, the distinguished illustrator of British Carcinology, 

 the late William Elford Leach. 





