I. '08. 



90 



This species is not very common in Irish waters. In the 

 Irish Sea it has only been found three times, but it has been 

 taken on several occasions off the north coast in soundings of 

 110-130 fathoms, and off the west between 470 and 627 

 fathoms. 



In addition to the colour distinctions noticed above, the west 

 coast specimens differ from those found in the north and east 

 in the longer rostrum, more slender pereiopods, and larger 

 eyes. In figs. 1 and 2 is shown the anterior part of an east 

 coast specimen measuring 52' 5 mm.^, w^hile figs. 3 and 4 repre- 

 sent the same views of an example from deep water on the 

 west coast measuring 57 mm.^ These figures give an idea of 

 the range of variation in the size of the eye and length of the 

 rostrum which exists in the collection. 



The following tables show the relation which the length of 

 the rostrum bears to the length of the body in all the perfect 

 specimens obtained : — 





West coast. 







470-627 fathoms. 





Sex. 



Length 



of 

 body.i 



Length 



of 

 rostrum. 



Ratio of 

 rostrum to 

 body (100). 



^ 



57 ' 29 



50 



6 



49 29 



59 



<5 



44 27 



61 



9 



41 21-5 



52 



9 



38 18 



47 





East Coast. 







34-42 fathoms. 





Sex. 



Length 



of 

 body. I 



Length 



of 

 rostrum. 



Ratio of 

 rostrum to 

 body (100). 



9 



52-5 



20 



38 



9 



51 



19 



37 



6 



40 



13 



32 





NORTH Coast. 







110-130 fathoms. 





Fex. 



Length 



of 

 body.i 



Length 



of 

 rostrum. 



Ratio of 

 rostum to 

 body (100). 



9 



51 18 



35 



1 ■ ^ <? 



45 15-5 



34 



! 6 



42 1 14 



33 



1 



6 



41-5 



16 



38 



6 



41 



15-5 



38 



9 



40 



16 



37 



6 



39 



16 



41 



6 



39 



15 



39 



6 



32-5 



14 



43 



9 



25 



9 



36 



The average length of the rostrum, compared with the body, 

 is found to be 54 per cent, in the case of the west coast ex- 

 amples, while in those from the north and east it is 36 J per 

 cent, and 35 1 per cent. Unfortunately the specimens are so 

 few in number that little reliance can be placed on such data : 

 nevertheless it seems probable that the deep waters of the 

 Irish Atlantic slope are inhabited by a race of P. propinquus 



1 Measured from the back of the orbit to the apex of the tehon. 



