223 NOTES ON SOME SCOTTISH MARINE ISOPODS 



coast. The second has been taken " rather plentifully in the 

 Christiania Fjord in quite shallow water among eel-grass " ; it is 

 also recorded by Hoek from botli the Dutch and French coasts. 

 I. viridis is nearly of the same length as I. pelagica, but is much 

 narrower, " being more than four times as long as broad/' and is 

 of a uniformly greenish colour. 



Astacilla longicornis {Sowerby). 



This is the Arcturus longicornis of Bate and Westwood's 

 "Sessile-eyed Crustacea." It has been shown, however, that Arcturus 

 is not only of later date than Astacilla, but refers to a different 

 genus. Astacilla longicornis is, under the name of Arcturus, 

 recorded from several Scottish localities. Sars considers the 

 Arcturus gracilis of Goodsir to be the adult male of A. longicornis. 



Arcturella dilatata, G. O. Sars. 



The late Dr. Robertson records this for the Clyde under the 

 name of Leacia dilatata. Professor Sars has, for reasons stated by 

 him, established a new genus {Arcturella) for this Isopod. Dr. 

 Robertson's is the only Scottish record known to me for this species. 



Lera marina (Fabricius). 



Professor Sars adopts Fabricius' specific name in preference to 

 albifrons of Leach. " There cannot," he says, " be any doubt that 

 the Oniscus niarinus of O. Fabricius is this species," and, being the 

 older name, ought to be preferred to that of Leach. He is also 

 doubtful if the Icera Nordmanna figured by Bate and Westwood is 

 Rathke's species of that name ; it seems rather to be the male of 

 I. marina. 



Munna Boecki, Kroycr. 



This species may be distinguished from Munna Kroycri by its 

 greater size, and especially by the structure of the superior antenna; 

 in the adult and by the armature of the caudal segment. The 

 flagellum of the superior antennae in the adult is usually six-jointed, 

 but in immature specimens the number of joints is less ; the caudal 

 segment resembles that of M. Kroyeri in having the anterior portion 

 of both margins armed with a few prominent spiniform teeth, but 

 differs in having the apical lamellae also coarsely serrated. A 

 number of specimens of M. Boecki with ova occurred in a gathering 

 of the micro-crustacea from the vicinity of Ailsa Craig, Firth of 

 Clyde, collected in April 1897, and it has also been obtained in 

 Kilbrennan Sound. In the Moray Firth and in the Firth of Forth 

 immature specimens apparently belonging to the same species have 

 also been observed. 



