LIST OF ILLUSTRATIONS 



Frill-Gilled Shark, 

 Angel-Fish, 

 Japanese Saw-Fish, 

 Halavi Ray, 

 Thornback Skates, 



PAGE 



533 



536 

 537 



539 



540 



PAGE 



Jaws of Thornback, . . 541 



Common Skate and Marbled Electric Ray, 542 



Teeth of Lobe-Finned Shark, . . 546 



Restoration of Fold- Finned Shark, . 547 



Restoration of Spine-Firmed Shark, . 547 



THE LOWEST VERTEBRATES AND THEIR ALLIES 



PAGE 



Group of Lampreys, . . .551 



Hag-Fish, . . . . .553 



Skeleton of Primeval Lamprey, . . 554 



Restoration of Pteraspis, . . . 555 



Restoration of Cephalaspis, . . 556 



Restoration of Pterichthys, . . . 556 

 Lancelet, ..... 558 



A Leathery Sea- Squirt (Microcosmus), . 561 



Section of Sea-Squirt, . . .562 



PAGE 



A Cartilaginous Sea-Squirt (Phallusia), . 565' 



Pear-Shaped Ascidian (Hypobythius), . 566 



A Creeping Ascidian (Clavelina), . . 567 



An Incrusting Ascidian (Botrylloides), . 568 



A Compound Ascidian (Amarucium), . 568 



An Individual of a Chain-Salpa, . . 570' 



Botryllus, ..... 572 



Young Balanoglossus, . . .573 



A Pyrosoma Colony, . . . 576' 



