4 MARINE AND FRESHWATER FISHES 



Marsipobranchii, comprising the Lampreys ; and VI. The 

 Pharyngobranchii, represented only by that lowest known 

 and very remarkable vertebrate form, the Lancelet, Amphi- 

 oxus. Of the six foregoing groups, but one, that of the 

 Dipnoi, is wanting to our indigenous fauna. This order, 

 which among existing forms includes only the African and 

 American Mud-fishes Protopterns and Lepidosiren, and the 

 Australian Ceratodus, is of especial interest to the biologist, 

 since it constitutes a stepping-stone to the tailed amphibia, 

 or Newts and Salamanders, with which, indeed, anatomi- 

 cally, the species possess many points in common. The 

 African type, Lepidosiren annectans, has been frequently 

 brought alive to this country, and several fine casts, illus- 

 trating its singular form, are on view in the Buckland 

 Museum. A figure of the yet more remarkable and very 

 recently discovered Ceratodus miolepis, inhabiting the fresh 

 waters of Queensland, Australia, is given overleaf. The 

 enumeration and description of our highly representative 

 British fish-fauna may now be proceeded with. 



ORDER l.—Teleostei. 



Fishes having a spinal column that always contains dis- 

 tinctly ossified vertebral centra, and the primordial cartilage 

 of the skull more or less completely replaced by bone. 



SUB-ORDER I.— Spine-finned Fishes 

 (A canthopterygii) . 



A greater or less portion of the rays of the dorsal, anal, 

 and ventral fins not articulated, but represented by sharp- 

 pointed indurated spines ; the lower pharyngeal bones 

 usually distinct. Air-bladder in the adult fish without a 

 pneumatic duct. 



