I. '08. 



124 



from one another, but in the west such a great diversity of 

 form is apparent that if it were not for the long series of inter- 

 mediate examples, the creation of at least two additional 

 species would be justifiable. 



Two large specimens selected at random from the Irish Sea 

 material and from the west coast collections compare as fol- 

 lows : — 



Irish Sea. 



$ 67 mm. 



Form slender, abdomen 

 one-third as deep as long. 



Antennal scale one-half the 

 length of the carapace and 

 nearly six times as long as 

 wide. 



Penultimate joint of anten- 

 nular j)eduncle nearly twice 

 the length of the ultimate. 



Third maxillipedes reaching 

 beyond the apex of the anten- 

 nal scale by little more than 

 the ultimate joint. 



Fifth pereiopod reaching 

 beyond the apex of the anten- 

 nal scale by the dactylus only. 



Bofin Harbour, Co. Gal way. 



$ 45 mm. 



Form stout, abdomen one- 

 half as deep as long. 



Antennal scale almost 

 three-quarters as long as the 

 carapace, and scarcely four 

 times as long as wide. 



Penultimate joint of an 

 tennular peduncle about one 

 and a quarter times as long 

 as the penultimate. 



Third maxillipedes reach- 

 ing beyond the apex of the 

 antennal scale by the w^hole 

 of the two ultimate joints. 



Fifth pereiopod reaching 

 beyond the apex of the an- 

 tennal scale by rather more 

 than the propodus and dac- 

 tylus. 



In both these specimens the second pair of pereiopods are, 

 as usual, of unequal length, but in other examples from the 

 west coast a very remarkable degree of variation exists in this 

 respect, for in many cases the long right-hand pereiopod is 

 very considerably shortened, in some instances to such an ex- 

 tent that both right and left are exactly equal and do not 

 reach beyond the antennal scale by more than the length of the 

 chela. 



The principal variations observed in the series of Irish speci- 

 mens may be summarised thus : — 



Form of carapace and abdomen stout or slender. 



Eye scarcely wider than, or fully one and a half times as 

 wide as, the greatest breadth of the antennal scale. 



Rostrum falling slightly short of, or extending a little 

 beyond tjie eye. 



