CONTENTS 



PAGE 



Order 2. HOLOCEPHALI 168 



Group A 176 



Fam. 1. Squalorajidae, 176 ; Fam. 2. Myriacauthidae, 176. 



Group B . 176 



Fam. 1. Callorhynchidae, 176 ; Fam. 2. Chimaeridae, 176 ; 



Fam. 3. Ehinochimaeridae, 178. 



INCERTAE SEDIS. Fam. 1. Ptyctodqntidae, 179 ; Fam. 2. Mena- 



spidae, 180. 



Sub-Class 2. PLEURACANTHODII . . 180 



Fam. 1. Pleuracanthidae, 183; Fam. 1 2. Cladodontidae, 183; 

 Fam. 3. Chondrenchelyidae, 183. 



Sub-Class 3. CLADOSELACHII 184 



Fam. Cladoselachidae, 187. 



Sub-Class 4. ACANTHODII 187 



Fain. 1. Diplacanthidae, 192 ; Fam. 2. Acanthodidae, 192. 

 INCERTAE SEDIS. Fam. Gyracanthidae, 192. 



Sub-Grade 2. OSTRACODERMI 194 



Order 1. PTERASPIDOMORPHI . ... 195 



Fam. 1. Coelolepidae, 196 ; Fam. 2. Drepanaspidae, 197 ; 

 Fam. 3. Psarnmosteidae, 198 ; Fam. 4. Pteraspidae, 198. 



Order 2. CEPHALASPIDOMORPHI . . 200 



Fam. 1. Ateleaspidae, 203 ; Fam. 2. Cephalaspidae, 203 ; 

 Fam. 3. Trernataspidae, 204. 



Order 3. ANASPIDA . . 204 



Fam. 1. Birkeniidae, 205 ; Fam. 2. Lasaniidae, 205 ; Fam. 3. 

 Euphaneropidae, 206. 



Order 4. PTERICHTHYOMORPHI . . 206 



Fam. Asterolepidae, 209. 



Sub-Grade 3. OSTEICHTHYES 210 



Scales, 210; Lepidotrichia, 212; Cranial bones, 213; Ganoid 

 scale, 214 ; Lateral line, 219 ; Air-bladder, 223 ; Nostrils, 227 ; 

 Chief characters, 227. 



DIAGRAM OF PHYLOGENY, 228. 



Group A 230 



Sub-Class 1. DIPNOI 230 



Scales, 230 ; Dermal rays, 232 ; Vertebral column, 233 ; Skull, 

 236 ; Girdles and fins, 242 ; Brain, 245 ; Gills, 247 ; Blood- 

 vascular system, 248 ; Urinogenitals, 253; Chief characters, 254. 



