264 REPORT— 1902. 



annatus, we must now recognise a species of southern or Mediterranean 

 origin, in which the endopodite of the second foot consists of only one 

 segment, while in the Faroe Channel and northern regions a species very 

 closely congeneric has a definitely biarticulate endopodite. Other points 

 of ditference exist in the character of the rostrum and the spiny pro- 

 longations of the last thoracic segments, both of which in the southern 

 species are much stronger. Possibly a third species of uEtideus exists in 

 the examples recorded by Brady from the Indian Ocean and described in 

 the ' Challenger ' reports ; but this species must for the present remain in 

 doubt, since it has not been met with again. The autlior would remark 

 that in a collection of Copepods made by Mr. J. Stanley Gardiner in the 

 Maldive Islands and forwarded to him for examination, lie has not met 

 with a .single example of uEtideus. 



Similarly in the genus Gaidius (Giesbrecht) there is one species 

 having a uniarticulate endopodite of the second foot, and another species 

 in which this ramus is biarticulate. The exopodites of the first feet also 

 show irregularity in their segmentation. For instance, the genera 

 jEtidetis, Bradyidins, Bryaxis, Chiridius, have this appendage tri- 

 articulate, while in Gaidius and Gaetanus it is biarticulate, or in one 

 species of the latter (G. arniir/cr) three jointed. 



The appendages of the first basal joint of the fourtli pair of feet become 

 of importance generically. In his original description of the genus Gaiditis 

 Giesbrecht had already remarked upon the peculiar transformation of the 

 bristles of this joint into lamellar appendages, as transitional to the 

 spines of Euchirella. These modified bristles, which ajipear to be hollow 

 tubes, are very characteristic of the genera Gaidlnn and Gae/amis. They 

 are replaced by spines and teeth in the genus Euchirella. The character 

 of the rostrum and its presence or absence appear to form a satisfactory 

 basis for the classification of the genei-a of the sub-family ^Etidiitice, and 

 have been adopted in the present scheme. 



Recently Professor Sars has expressed the opinion that the genus 

 Gaidius (Giesbrecht) should be abolished, and he has considerably 

 extended the genus Cliiridius by inclusion of three species {Ch. tenui- 

 spinus, Ch. obtusifrons, and Ch. armatus). But the genus as originally 

 proposed by Giesbrecht, to include the only species known as yet, viz., 

 Ch. poppei, appears to difler very considerably from Sars' genus 

 Chiridius ; and one of the latter species, viz., Ch. tenuisi>inus (Sars), 

 is undoubtedly identical with Giesbrecht's GaMius. One essential point 

 of generic diflerence is the absence of a rostrum in Giesbrecht's genus 

 Chiridius, and its presence in two at least of Sars' species {Ch. tenuispinus 

 and Ch. armatus). Professor Sars lately had the kindness to forward to 

 me examples of these three Copepods from his own collections, and from 

 a comparison of Giesbrecht's preparations I have no doubt in affirming 

 that Chiridius tenuispinus, Sars, is identical with Giesbrecht's Gaidius, 

 and with specimens which the authof had described previously as Gaidius.^ 

 In addition to the presence of a rostrum, the bristles of the first basal 

 joint of the fourth pair of feet are modified into tubal processes exactly as 

 in Gaidizis pungens (Giesbrecht). 



The genus Chiridius, as at first proposed by Giesbrecht (' Fauna ii. Flora 

 Neapel,' v. 19), included only one species. It differs from all other genera 

 of this group, in the fact of the outer branch of the posterior antennse 

 being twice as long as the inner, and in the presence of only eight bristles 



' See Journ. lirit. Marine Biol. Amuc, 1901. 



