- 



APPENDIX 



CLASSIFICATION OF THE VERTEBRATA. 



The following list of the larger subdivisions of the Vertebrata, 

 arranged in synoptical form, may be of use in explaining the 

 names of groups as used in the body of the work. Through 

 the labors of palaeontologists so many forms have been unearthed 

 and so many new groups established that it seems best to include 

 in the list these latter as well as modern animals, especially since 

 many of the extinct groups consist of generalized forms from 

 which several living groups have differentiated. The names of all 

 groups, of whatever rank, that contain living representatives are 

 printed in bold-faced type; those groups in which these latter 

 are represented by but one or two isolated forms are farther 

 designated with an asterisk. In this way the amount of dam- 

 age wrought in the phylogenetic record, as well as the relative 

 position of the groups, may be seen at a glance. The synopsis 

 follows : 



VERTEBRATA (or Chordata). 

 Division I. Cyclostomata.* 



Class I. Marsipobranchii.* 

 Sub-Class I. Cyclostomi.* 



Order I. Myxinoidea * (Myxine, the hag-fish). 

 Order 2. Petromyzontoidea * (Petromyzon, the 

 lamprey eel). 



Sub-Class II. Ostracodermi. 



Order i. Heterostraci (Pteraspis). 

 ' Order 2. Osteostraci (Cephalaspis). 



Order 3. Antiarchi (Pterichthys). 



539 



