484 



Mr. C. T. Regan on the Origin and 



the skull. As he gives the number of vertebrae as 21 it 

 seems probable that in the preparation of the skeleton the 

 first vertebra adhered to the cranium, and was then removed 

 separately and perhaps lost. 



Subfamily 2. Capeoinje. 



Mouth extremely protractile; praemaxillary processes very 

 long, separating the frontals and extending back beneath the 

 supraoccipital; maxillary narrow, without suprarmixillary ; 

 a broad subocular shelf. Spinous dorsal not shorter than the 

 soft-rayed fin. 



The Miocene Proantigonia, Kramberger, is closely allied 

 to the recent Capros, Lacep. 



L1V. — The Origin and Evolution of the Teleostean Fishes of 

 the Order Heterosomata. By C. Tate ReGAN, M.A. 



(Published by permission of tbe Trustees of the British Museum.) 



The Heterosomata, or Flat-fishes, differ from all other fishes 

 in their asymmetry; both eyes are on one side, which is 

 coloured, whilst the eyeless side is usually white. 



Fiff. 1. 



A. B. 



Disarticulated frontal bones of (A) Halibut {Hijipoylossiis kippofflossus) 

 and (B) Plaice (Pleuro?iectes platessa) . (After Traquair.) 



pfa, prefrontal articulation ; ip, interorbital process ; i, interorbital bar. 



In the skull of all flat-fishes there is a bony interorbital bar 

 mainly formed by the interorbital portion of the frontal bone 



