LIST OF ILLUSTRATIONS xv 
PAGE 
Frill-Gilled Shark, 
. 533 
Angel-Fish, 
. 536 
Japanese Saw-Fish, 
. 537 
Halavi Ray, 
. 539 
Thornback Skates, 
. 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-Finned Shark, . 547 
THE LOWEST VERTEBRATES AND THEIR ALLIES 
Group of Lampreys, 
Hag-Fish, .... 
Skeleton of Primeval Lamprey, . 
Restoration of Pteraspis, . 
Restoration of Cephalaspis , 
Restoration of Pterichthys,. 
Lancelet, .... 
A Leathery Sea-Squirt ( Microcosmus), 
Section of Sea-Squirt, 
PAGE 
551 
553 
554 
555 
556 
556 
558 
561 
562 
A Cartilaginous Sea-Squirt ( Phallusia ), 
Pear-Shaped Ascidian (. Hypobythius ), 
A Creeping Ascidian ( Clavelina ), . 
An Incrusting Ascidian ( Botrylloides ), 
A Compound Ascidian ( Amcirucium ), 
An Individual of a Chain-Salpa, . 
Botryllus, .... 
Young Balanoglossus, 
A Pyrosomci Colony, 
PAGE 
565 
566 
567 
568 
568 
570 
572 
573 
576 
