CONTENTS 



PACK 



Order 2. HOLOCEPHALI . . 168 



Group A ...... . . 176 



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

 Group B .176 



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

 Fam. 3. Rhinochimaeridae, 178. 



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

 spidae, 180. 



Sub-Class 2. PLEURACANTHODII . .180 

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

 Fam. S^Chondrenchelyidae, 183. 



Sub-Class 3. CLADOSELACHII .184 



Fam. Cladoselachidae, 187. 



Sub-Class 4. ACANTHODII - .187 



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

 INCERTAE SEDIS. Fam. Gyracanthidae, 192. 



Sub-Grade 2. OSTRACODERMI - 19* 



Order 1. PTERASPIDOMORPHI . . . . .195 

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

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



Order 2. CEPHALASPIDOMORPHI . . . ' T 200 



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

 Fam. 3. Tremataspidae, 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. 



