I. '08. 



85 



distinct. The three genera may be thns separated in tabular 

 form : — 



I. Eostriim at least as long as carapace ; branchial formula : — 



— 



VIL 



VIII, 



1 

 IX. 



X. 



XL 



xn. 



XIIL 



XIV. 



Podobranchiae, 



... 



1 + ep. 



ep. 



ep. 



ep. 



ep. 



ep. 





Arthro branchiae, 





... 



2 



1 



1 



1 



1 





Pleurobranchiae, 



... 







1 



1 



1 



I 



1 



A . Lateral process of antennules distally broad and 



rounded ; posterior lobe of exopod of second 

 maxilla acutely pointed ; second pair of pereio- 

 pods unequal, ...... PandaJus. 



B. Lateral process of antennules acutely pointed 



distally ; posterior lobe of exopod of second 

 maxilla broadly rounded ; second pair of pereio- 

 pods subequal, .... Plesionika (p. 93). 



II. Rostrum not more than half the length of the 

 carapace ; posterior lobe of exopod of second 

 maxilla truncate, branchial formula : — 



VIL 



1 



\t;il 



IX 



X 



1 

 XI. 



XTL 



xm. 



XIV. 



1 



1 

 Pleurobranchiae, 



! 

 1 



l+ep. 



ep 



ep. 



ep. 



ep. 



ep. 





Arthrobranchiae, 







2 









... 





Pleurobranchiae, 



1 

 1 







1 



1 



1 



1 



1 



Pandalina (p. 97). 



Genus Fandalus, Leach. 



Dichelopandalus , Caullery. 



Four species of this genus have been found in British and 

 Irish v^aters ; they may be separated thus^ : — 



I. Third maxillipede without exopod. 



A . Carpus of second pereiopod on right side with 

 many (at least twenty) annulations ; an- 

 tennal scale not much narrowed in front, 

 outer edge straight. 



1 Caiman's admirable paper on the British Pandalidae (1899) contains 

 descriptions and figures of Pandalina brevirostris and of the species of 

 Pandalus (excepting P. horealis, which was not then known to occur in 

 British waters). The above ' table is borrowed from this work, P. 

 boreaUs being included. 



