THE DIPNOI. 



145 



Ganoids, the Teleostei are not known before the Cretaceous 

 epocli, when both Physostomi and Acanthopteri make their 

 appearance, under forms, some of which (e. g., Beryx) arc 

 generically identical with fish living at the present day. 



VI. The Dipnoi.— The " Mudfishes " of the rivers of the 

 east and west coasts of Africa and of eastern South America 

 are nearly transitional forms between the Pisces and the Atn- 

 phibia. 



The eel-like body, covered with overlapping cycloid scales, 

 tapers to a point at its caudal extremity, and is provided with 

 two pairs of long, ribbon-like, pointed extremities, and with a 

 caudal fin. 



Pig. 51.— Tbo Mudfish (J^^pidosiren). 

 C Or ? 



M/n 



Fifl, 52. — Skull ot Lepido siren annectens: A, the uarieto-frontal bone ; .S, the supra-orbi- 

 tal ; C, the nasal ; D, the palato-pteryg:oid ; ^, tne vomerine leetn ; ^, (3., the ex-occlpl 

 tal ; Mn, the mandible ; Jfy, the hyoid ; Br, the branchiostegal rays ; Op, the opei-cular 

 plate : a), the parasphenoid ; y, the pharyngo-brancMal ; Or, the orbit ; Au, the auditcry 

 chamber ; 27\ the nasal sac 



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