Notes on the British Species of Zeugopto.rus. 3G3 



and 2'>^f^'^ctatus — under the genus Zeugojjterus, 11. unimaculatus 

 not being met with in Norwegian waters. This species, 

 however, is found in the Mediterranean, and has been in- 

 cluded in the genus Zeugopterus by Giglioli (8). It will thus 

 be seen that the genus Zeugopterus is made to include species 

 in which the ventrals are free from the anal, and also one 

 {Z. punctatus) having the ventrals united with the anal. 

 The condition of the ventral fins ceases therefore to be of 

 generic value. 



Eecently Day (9) has rearranged the Biitish species as 

 follows : The R. megastoma of Donovan is included in 

 Bleeker's genus Arnoglossus, along with the mergrim, A. 

 laterna. B. norvegicus, a species which has not yet been 

 found in British waters, would also probably be included in 

 this genus. The remaining species — viz., B. punctatus and 

 B. iinimaculatus — form the genus Zeugopterus as understood 

 by Day. Thus the second and third divisions of the genus 

 PiHOMBUS, as defined by Gottsche, have been broken down, 

 and the genus Zeugopterus, as recently defined, includes 

 species in which the ventrals may or may not be united to 

 the anals, the generic characters depending on other features. 

 The following are the characters defined by Day : " Branchios- 

 tegals, seven ; pseudobranchise present ; eyes on the left side, 

 and close together; cleft of mouth deep; sharp villiform 

 teeth in a band in either jaw, present or absent from the 

 vomer. The dorsal fin commences before the upper eye ; its 

 rays and those of the anal are nearly all branched ; caudal 

 not united to the vertical fins ; the ventrals either free from 

 or united to the anal ; scales ctenoid ; lateral line having a 

 strong curve anteriorly." 



The majority of these characters are not confined to the 

 genus Zeugopterus, but are also common to the genera Bhomhus 

 and Arnoglossus. 



An examination of the British species of Blturonedidm 

 will show^ that the genera fall more or less naturally into 

 three groups, Bhomhus and its allies occupying an inter- 

 mediate position between Hippoglossus and Pleuronecies. In 

 order to grasp more surely the relation of Zeugopttrus to 

 the other Pleuro7iectidcr, I subjoin a table, showinir this 



