441 Canon A. M. Norman on British Isopoda. 



genus ; and at the head of this description the name stands 

 Idotea, and that this was no accidental error is proved by the 

 same spelling being repeated in a footnote " Idotece."" But 

 in the * Index Alphabeticus ' of that supplement, published 

 in the following year (1799), we find again the spelling 

 Idothea. Thus the Indexes give Idothea^ but the name with 

 the description is Idotea. There seems therefore room for a 

 divergence of opinion as to which spelling should be more 

 properly employed. It appears to me right to retain the 

 spelling Idotea — first, because this is the spelling which is 

 used, and intentionally used, witli the description; secondly, 

 because it is the spelling which has been almost universally 

 employed for a hundred years ; and, thirdly, because Idotea 

 is more euphonious than hlothea. The name itself appears 

 to be a " nomen proprium •" without any derivation. 



Genus 1. Idotea, J. C. Fabricius. 



In my paper '^ A Month on the Trondhjem Fiord " (Ann. & 

 Mag. Nat. Hist. ser. 6, vol. xiii. 1894, p. 279) I called 

 attention to several distinct varieties of what was there called 

 Idotea marina ( = /. halthicd). These varieties have been 

 elevated by Sars to specific rank, and the Mediterranean form, 

 my " var. c?," must equally with these be regarded as a species 

 and bear the name /. Basteri, Audouin. As long ago as 

 1777, Pennant regarded two forms on our coast as distinct 

 species and named them Oniscus marinus ( = /. granidosa, 

 Rathke) and 0. entomon ( = /. buUhica, Pallas). 



1. Idotea halthica (Pallas). 



This is Idotea triciispidata, Desmarest and Bate and 

 Westwood, /. tridendata, Rathke, and I. marina, Miers and 

 Norman (/. c). On the N.E. American coast it has been 

 known as /. irrorata (Say), under which name I have speci- 

 mens from Vineyard Sound (J/r. Ilarger) and lat. 40° 06' N., 

 long. G8° 01' W. (Smithsonian Institute). Professor Sars 

 considers the Oniscus marinus, Linne, to be what we have 

 known as Icera alhifrons and not an Idotea, and has followed 

 Fabricius in applying the specific name to the former 

 species. 



/. haJtJdca is the species figured by Bate and Westwood 

 under the name 1. tricuspidata (vol. ii. p. 379). It is found 

 all round our coasts. 



2. Idotea granidosa, Ttathke. 



1843. Idotea graindosa, Ratlike, Beltrage zur Fauna Norwegens, p. 23. 



