GENERAL CLASSIFICATION. 



427 



General Classification. 



Amniota, embryos with amnion and allantois. 



Fishes. — t\£-.Dipnoi(double-breath- 

 ing mud-fishes). — 



Teleostei (modern bony 

 fishes). 



Ganoidei (sturgeon, etc.). 



Elasmobranchii (skate, 

 shark, etc.). 



■ Amphibians. — 



- Anura (tailless frogs, etc.). 

 Urodela (tailed newts, etc.). 

 Gymnophiona (worm-like Cce- 



cilia, etc.). 

 Extinct Stegocephali (Laby- 

 rinthodoH) etc.). 



Ichthyopsida (fishes and amphibians). 



Cyclostomata (Round Mouths), without true jaws. 

 Myxine, hag-fish. Petromyzon, lamprey. 



Cephalochorda. — A mpkioxus 

 Lancelet. 



r Saiga type. 

 ., I Ascidian type (sea- 



Ubochorda or J ^ 



Iunicata. \Appendicularia (lar- 

 V val type persistent). 



Surviving offshoots of ancestral Vertebrates. 



Hemichorda or Enteropneusta (offshoots of incipient Vertebrates?) 



Balanoglossus, etc. ; probably Cepkalodiscus ; possibly Rhabdopleura. 



Nemertean affinities (?) Chsetopod affinities (?) Arthropod affinities (?) 



Ancestry of Vertebrates. 



It is not at present possible to trace the path along which Vertebrates 

 have evolved, though our faith in the doctrine of evolution— as a modal 



