A REVISION OF THE BRITISH IDOTEID^E. 725 



Dana (16) in .1853 to a large extent followed the main lines of Milne-Edwards' 

 classification. 



Kinahan (37) in 1857 very thoroughly and critically examined the different systems 

 up to that date, and at once recognised the importance of the antennae and the uro- 

 poda, and, he adds, perhaps the form of the maxillipedes, but he states : " Two very 

 important sets of characters have been omitted or overlooked, which must be taken 

 into account in any classification which seeks to form natural groups ; these are : the 

 characters drawn from the form of the head and from the epimerals " (coxal places). 



It is upon the whole of the above-mentioned characters that the classification 

 in the present paper is based. 



The leading structural characters of systematic value are undoubtedly shown in 

 the form of the cephalon and its appendages, the coalescence of the abdominal 

 segments, and the operculiform inferior uropoda. In all of these characters the 

 Idoteidse exhibit a close relationship with the Arcturidae. Both families are 

 probably of ancient origin, and many of their genera afford evidence of more recent 

 modifications and adaptations. Unfortunately many of the earlier species are in- 

 completely described and still more incompletely figured, as already pointed out. 

 Ohlin (48) very pertinently remarks, the classification of the different genera 

 is as yet very uncertain, and is very much in want of a renewed critical revision. 

 Such a revision the writer hopes to complete at no very distant date. 



Latreille (39) in 1829 included in his fourth section of the family (the Idoteides 

 of Leach) the genera Idotea, Fabricius ; Stenosoma, Leach ; and Arcturus, Latreille. 

 Milne-Edwards (45) in 1840 employed the same section for the genera Arcturus, 

 Idotea, and Anthura, Leach, but this last-mentioned genus has little in common 

 with either of the preceding ones, apart from the elongated form of the body. 



In 1853 Dana (16) removed the Arcturidae to a new group, which he termed 

 Anisopoda, and placed the Idoteidae with the Chaetiliidae, a proceeding which few 

 subsequent authors have thought was warranted. Of the three genera he described, 

 Epelys, Cleantis, and Erichsonia, the first is now regarded as synonymous with 

 Edotia, Guerin-Men., the second with Zenobiana, Stebbing, and for the third name, 

 which was preoccupied, Benedict substituted Ericlisonella. 



Bate and Westwood (3) in 1867 associated together the families Arcturidae and 

 Idoteidae. Claus (12) in 1871 placed both Chsetilia, Dana, and Arcturus in his 

 group Idoteides. 



Both Harger (32) in 1880, and Miers (44) in 1881, recognised the close affinity 

 of the Idoteidae with the Arcturidae, as have practically all subsequent authors. 

 Bonnier (5) in 1887, following Claus, placed both Arcturus and Idotea in the family 

 Idotheidae. Hansen (30) in the same year gave an account of Glyptonotus entomon 

 (Linn.), and figured and described some of the oral appendages. Dr Hansen 

 informs me (in litt. 7th Dec. 1915) that he now considers the specimens he examined 

 to be referable to the G. sibiricus of Birula. 



