CONTENTS 



THREAD-WORMS (Nemathelmia) 



Page 



Structure of a Round-Worm (Ascaris). Vinegar-Eel (Anguillula), Gordian- 



Worm (Gordius), Thorn-headed Worm (Echinorhynchus) 447 



CHAPTER XI 



STRUCTURE AND CLASSIFICATION OF ECHINODERMS 

 (Echinodermata) 



Structure of the Common Star-Fish (U raster rubens) 450 



Class I. — Star-Fishes (Asteroidea) 454 



Class 2. — Brittle-Stars (Ophiuroidea) 455 



Class 3. — Sea-Urchins (Echinoidea) 456 



Class 4.— Sea-Lilies and Feather-Stars (Crinoidea) 459 



Class 5. — Sea-Cucumbers (Holothuroidea) 462 



CHAPTER Xn 



STRUCTURE AND CLASSIFICATION OF ZOOPHYTES (Ccelenterata), 

 SPONGES (Porifera), AND ANIMALCULES (Protozoa) 



ZOOPHYTES (Ccelenterata) 



Structure and Development of the Fresh-water Polype (Hydra), taken as a 



Type. Comparison with higher forms. Cells and tissues - 465 



Class I.— SEA-FLOWERS (Actinozoa or Anthozoa) 473 



Structure of the Beadlet (Actinia mesembryanthemum), taken as a Type 473 



Order i. — Six-RAYED Sea-Flowers (Hexactinia) 474 



(i) Sea-Anemones — (2) Corals. 

 Order 2. — Eight-rayed Sea-Flowers (Octactinia) 476 



Structure of the Dead-Man's Fingers (Alcyonium digitatum), taken as a 

 Type. Organ-Pipe Coral (Tubipora musica), Red Coral (Corallium 

 rubrum), Sea-Pens and Sea-Mats. 



Class 2.— HYDROIDS (Hydrozoa) 478 



Structure and Development of Obelia, taken as a Type - 478 



Order i. — Budding Hydroids (Hydromedusae) 480 



(i) Hydroid Zoophytes and "Naked-eyed" Medusse — (2) Compound Jelly- 

 Fish (Siphonophora). 

 Order 2. — Splitting Hydroids (Scyphomedusa) 481 



Class 3.— COMB JELLY-FISH (Ctenophora) 483 



Structure of Cydippe. Venus's Girdle, Beroe, Creeping Ctenophores. 



SPONGES (Porifera) 



Structure of a Simple Sponge 484 



(i) Calcareous Sponges— (2) Siliceous Sponges. 



ANIMALCULES (Protozoa) 



Protoplasm. Description of the Proteus Animalcule (Amoeba), taken as a 



Type. Comparison of Protozoa and higher forms (Metazoa) 484 



