CONTENTS ix 



I'AGK 



— Elops — Slender-Scales {Leptolepis) — The Smooth-Heads (A lepocephalidce) — Southern 

 Salmon (HaplochitonidoB) — Salmon Tribe (Sabnonidce) — Typical Group (Salmo) — 

 Salmon — Trout — Charr — Many-Rayed Salmon (Onchorhyn chus) — Smelts {Osmerus) — 

 Coregonoids (Coregonus) — Grayling (Thymallus) — Percopsidce — Bony Pike and its 

 Kindred (Suborder JEtheospondyli) — Existing Types (Lepidosteidce) — Spear-Beaks 

 (Aspidorhynchidce) — The Bow-Fin and its Allies (Suborder Protospondyli) — Existing 

 Family (Amiidm) — Extinct Families (Pachycormidce, etc.) — The Sturgeon Tribe (Sub- 

 order Chondrostei) — Toothed Sturgeons (Polyodontidce) — Toothless Sturgeons — (Acipen- 

 seridce) — True Sturgeons (Acipenser) — Shovel-Beaked Sturgeons (Scaphirhynchus) — 

 Allied Extinct Families (Chondrosteidce, etc.) — Fringe-Finned Ganoids (Order Cros- 

 sopterygii) — Existing Species (Polypteridce) — Extinct Families, .... 333 



CHAPTER IV. — Sharks and Rays, — Subclass Elasmobranchii. 



Distinctive Features — The Blue Shark and its Allies (Carchariidce) — Typical Genus (Car- 

 charias) — Tope (Galeus) — Hammerheads (Sphyrna) — Hounds (Mustelus) — Porbeagle 

 Group (Lamnidce) — Porbeagles (Lamna) — Rondeleti's Shark (Carcharodon) — Fox-Shark 

 (A lopecias) — Basking-Shark (Cdorliinus) — Indo-Paeinc Basking-Shark (IUiinodontidcv) 

 — Dog-Fishes and Their Allies (Scylliidce) — True Dog- Fishes (Scyllium) — Other 

 Genera — Pavement-Toothed Sharks (Cestraciontidce) — Comb-Toothed Sharks (Noti- 

 danidce) — Typical Genus (Notidanus) — Frill-Gilled Shark (Chlamydoselache) — The 

 Spiny Dog-Fishes and their Allies (SpinacidcB) — The Extinct Petalodonts (Petalodon- 

 tidce) — The Angel-Fish (Squatinidce) — The Saw-Fishes (Pristiophoridce and Pristidce) — 

 Side-Gilled Saw-Fishes (Pristiophorus) — True Saw-Fishes (Pridis) — Beaked Rays 

 (Rhinobatida;) — Typical Genus {Rhiuobatu) — Rhynchobatis — The True Rays, or Skates 

 (Raiidcc) — Electric Rays (Torpedinidce) — The Eagle-Rays (Myliobatidce) — Typical Genus 

 (Mylidbatis) — Other Genera (Aetobatis, etc.) — Sting-Rays (Trygonidce) — Lobe-Finned 

 Sharks (Ichthyotomi) — Fold -Finned Sharks (Oladodontia) — Spine - Finned Sharks 

 (Acanthodii), .......... 520 



THE LOWEST VERTEBRATES AND THEIR 



ALLIES 



CHAPTER I. — The Lamprey Group, — Class Cyclostomata. 



Characters of Chordates and Non-Chordates — Lampreys and Hag-Fishes (Subclass 

 Marsipobranchii) — True Lampreys (Petromyzwni) — Southern Lampreys (Mordacia, etc.) 

 — Hag-Fishes (Myxinidai) — Primeval Lampreys (Palceospondyhis), . . . 549 



CHAPTER II. — The Armoured Primeval Vertebrates,— Subclass Ostracoph 

 .Pteraspis—Cephalaspis Pterichthys, ........ 555 



CHAPTER III. — The Lancelets, — Subkingdom Protochordata — Class Leptocardii. 

 Common Lancelets (Branchiostoma), ........ 558 



CHAPTER IV.— The Sea-Squirts or Ascidians, Class Tunicata. 



Structure of Ascidians —Development Typical Ascidians Non-Luminous Pelagic Ascidians 



— Tailed Ascidians, ......... 561 



CHAPTER V. — Worm-Like Protochordates, Class Enteropneusta. 

 Balanoglosms — Other Forms — Ancestry of Chordates, .... . 573 



Ixdex to Fifth Volume, comprising Sections IX. and X. . . ■"" < 



