INTRODUCTION. ae 
INVERTEBRATE ‘ANIMALS. 
Sus-K1INGDOM I.—PROTOZOA. 
Animal simple or forming colonies, usually very minute; the body 
composed of the structureless, jelly-like, albuminous substance called 
“‘sarcode ;” not divided into regular segments ; having no nervous 
system ; no regular circulatory system; usually no mouth ; no definite 
body-cavity, or at most but a short gullet. 
Crass A. GREGARINID#.—Minute Protozoa which inhabit the in- 
terior of insects and other animals, and which have not the power of 
throwing out prolongations of their substance (pseudopodia). No mouth. 
Ciass B. RHIZOPODA (Root-footed Protozoa).—Protozoa which are 
simple or compound, and have the power of throwing out and retract- 
ing prolongations of the body-substance (the so-called “ pseudopodia”’). 
No mouth, in most, if not in all. ’ 
Order 1. Alonera.—Ex. Protogenes. 
Order 2. Amebea.—Ex. Proteus Animalcule (Amceba), 
Order 3. Foraminifera.—Ex. Lagena, Nodosaria, Globigerina. 
Order 4. Radiolaria.—Ex. Thalassicolla, Polycystina. 
Order 5. Stongita.—Lx. Fresh-water Sponge (Spongilla), Ve- 
nus’s Flower-Basket (Euplectella). 
Cuiass C. INFusoriIA (Infusorian Animalcules).—Protozoa with a 
mouth and short gullet ; destitute of the power of emitting pseudopodia; 
furnished with vibratile cilia or contractile filaments; the body usually 
composed of three distinct layers. 
Order 1. Cilata.—Ex. Bell-animalcule (Vorticella), Paramoecium, 
Order 2. Flagellata.—Ex. Peranema. 
Order 3. Szctorta.—Hx. Podophyra. 
'SUB-KINGDOM IJ.—C@LENTERATA. 
Animals whose alimentary canal communicates freely with the general 
cavity of the body ; body composed essentially of two layers or mem- 
branes, an outer layer or ‘ ectoderm,” and an inner layer or ‘‘ en- 
doderm.” No circulatory system or heart, and in most no nervous 
system. Skin furnished with minute stinging organs, or ‘‘ thread-cells.”’ 
Distinct reproductive organs in all. 
Cass A. HypRozoa.—Walls of the digestive sac not separated from — 
. those of the general body-cavity, the two coinciding with one another. 
Reproductive organs external. 
Sub-class I. Hyproipa (Hydroid Zoophytes). 
Order 1. Aydroida.—Ex. Fresh-water Polype (Hydra). 
Order 2. Corynida.—Ex. Pipe-coralline (Tubularia). 
Order 3. Sertularida.— Ex. Sea-firs (Sertularia). 
Sub-class II. StPHONOPHORA (Oceanic Hydrozoa). 
Order 4. Calycophoride.—Ex. Diphyes. 
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