116 



MR. R. GURNEY ON LEANDER LONGIROSTRIS 



between 70 and 80 per cent, of the length of the peduncle, and 

 the fused basal part is almost three-quarters of its total length 

 (between 70 and 75 per cent.). 



Table II. 



Dorsal rostral teeth of P. variayis. 



Number of teeth. 



Locality. 



Authoi'. 



Monfalcone, Istria j Brozek. 



Plymouth 



Forth Estuary, Scotland 



River Bure, Norfolk 



WftUs, Norfolk 



Maldon, Essex 



Stour Estuary, Suffolk .. 



Weldon. 

 Evans. 

 R. G. 



1. 



7. I 8. 

 10 I 1 



1 I 

 i 



2 ! 2 



7 i 



Second leg — Reaches, when extended, beyond the antennal 

 scales by the dactylus or part of the dactylus only. The dactylus 

 is about half the length of the palm. The carpus is very long, 

 and greatly exceeds the length of both the chela and the merus. 



The Telson. — The form and armature of the telson is very 

 constant throughout the Palsemonidse, and that of P. varians is 

 normally armed in precisely the same way as is that of the 

 British Leanders — namely with two pairs of small spines on the 

 dorsal surface, two pairs of large terminal spines, and a pair of 

 feathered setfe springing from beneath the merlian triangular 

 prolongation of the telson. There are, in addition, one or two 

 (normally one) small hairs on either side of the projection 

 dorsally. 



This arrangement of spines and setse is very variable in 

 P. varians from Norfolk. Out of 30 specimens taken in the 

 Eiver Bare only 17 were entirely normal, three more differed only 

 in having an additional pair of dorsal setse, and one in having an 

 additional minute ventral seta. The remaining nine were 

 strikingly abnormal in respect either of the number of terminal 

 spines or of ventral feathered setse, as follows : — 



One had only a single feathered seta in the middle line. 



Four had three of these setes. 



One had four, one had five, and one had six feathered setse. 



One had three pairs of terminal spines. 



The specimen with six setse (text-fig. 4B) is evidently a case of 

 the retention of the whole of the original seven pairs of larval 



