conte:n^ts. 



SKCnON PAGE 



I. The Stbucture of Amceba .1 



II. The Stkuctuee of Pabamcecxitm 7 



III. The Structure of Vorticella 12 



rv. The Multiplication of Vorticella . . . .19 



A'. Calcabeous Sponge 22 



VI. The Stbuctuke axd Growth of the Asexual Form 



of a Casipaxulaeiax Hydroid 30 



Vn. The Stbuctube of a>' Ocellate Hydro-Medusa . 37 



VIII. The Medusa Stage of a C ampajtul a ri a x Hydroid, 49 



IX. The Strcctcre of a Starfish : The Hard Parts . 56 



X. The Structure of a Starfish: Internal Anatomy, 63 



XI. The Microscopic Structure of the Starfish . . 73 



XII. The Hard Parts of a Sea-Urchin .... 83 



XIIL The Internal Structltie of a Sea-Urchin . . 91 



XIV. The Embryology and Metamorphosis of Echino- 



derms 99 



XV. The General Anatomy of the Earthworm . . 140 



XVI. The Microscopic Structure of thi Earth>\'orm . 152 



XVn. The General Anatomy of the Leech . . . 160 



XVHL The Hard Parts of the CoiiMON Crab . . . 168 



XTX. The Hard Parts of the Crayfish or Lobster . 185 



XX. The General Anatomy of a Crab .... 190 



XXI. The Metamorphosis of a Crab 207 



