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Bindicates

FIG. 197.
- Diagrammatic expression of classification in a genealogical tree.
possible position of Balanoglossus, D of Dipnoi, S of Sphenodon or Hatteria,

CHAPTER III

SYSTEMATIC ARRANGEMENT OF REPRESENTATIVE FORMS

SERIES I., PROTOZOA. — Animals without cellular tissues or true eggs.
Branch I. PROTOZOA. With same characteristics.

CLASS I. Rhizopoda. Having the power of throwing out pseudopodia.

Order 1. LOBOSA: - With short, blunt pseudopodia: Amaba.

Order 4. RADIOLARIA.

Order 2. FORAMINIFERA.

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With fine, anastomosing pseudopodia and calcareous shell; (single: Lagena. Order 3. HELIOZOA. With fine, stiff, radiating pseudopodia: Actinophrys.

compound: Nummulites.

With siliceous shell: Podocyrtis.

stage: Trichia.

CLASS II. Mycetozoa. - Terrestrial Protozoa, forming large amoeboid plasmodia and having plantlike spore

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CLASS III. Mastigophora. Having one flagellum or more, as the organ of motion: Euglena.

CLASS IV. Sporozoa. Consisting of one cell, and parasitic

Gregarina.

CLASS V. Infusoria. — Having cuticle, mouth, and cilia or tentacles.

Order 1. CILIATA. - Bearing vibratile cilia ;

fixed: Vorticella.

free: Paramecium.

Order 2. TENTACULIFERA. With suctorial tentacles: Acineta.

SERIES II., METAZOA. — Animals with cellular tissues, true eggs, and blastoderm. Branch II. PORIFERA. - Metazoa, with numerous incurrent openings, one or few excurrent orifices, generally a skeleton, independent cells.

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Skeleton, if present, of spongin fibers (Euspongia), or of siliceous spicules (Euplectella).

Subclass 2. NON-CALCAREA.

Branch III. COELENTERATA. - Radiate Metazoa, body consisting of two cell layers, with distinct digestive cavity, tentacles, and nettling thread cells.

CLASS

I. Hydrozoa. - Single digestive cavity, with which the mouth communicates freely.

Order 1. LEPTOLINE.

Fixed by adherent disk;

single: Hydra. compound: Eucope.

Order 2. HYDROCORALLINA. - With a skeleton of lime, forming a coral: Millepora.
Order 3. SIPHONOPHORA. - Free and oceanic, swimming by crested air sac: Physalia.
CLASS II. Scyphozoa. Having gastric tentacles.

Order 1. STAUROMEDUSE.-Cup-shaped, with marginal tufts of tentacles, and eight or more radiating canals; attached; single: Lucer

naria.

Order 2. DISCOMEDUSA. - Free and oceanic; disk-shaped, with marginal fringe of tentacles and " veil"; four canals; single: Aurelia. CLASS III. Actinozoa. - Double digestive cavity, with radiating septa.

Order 1. ACTINIARIA. — Parts in some multiple of five or six; soft-bodied; single; slightly locomotive: Actinia.

sclerodermic, rough, calcareous coral: Madrepora.

sclerobasic, smooth coral: Astræa.

Order 2. MADREPORARIA. — Parts in some multiple of five or six; composite; fixed; secreting

soft-bodied: Alcyonium.

Order 3. ALCYONACEA. Eight parts; composite; fixed;

Order 4.

secreting furrowed sclerobasic coral: Corallium. GORGONACEA.-Tree-like, spicules present in mesogloa: Gorgonia.

Order 5. PENNATULACEA. - Elongated colony with horny or calcareous AXIS: Pennatula.

CLASS IV. Ctenophora. - Soft-bodied; transparent; free, moving by eight rows of tiny paddles; two tentacles; diges

tive cavity with anal outlet: Pleurobrachia.

Branch IV. PLATYHELMINTHES. - Body generally flattened, no true metameric segmentation, no body cavity nor blood-vascular system.

CLASS I. Turbellaria. - Nonparasitic, with ciliated epidermis; digestive cavity present: Planaria.

CLASS II. Cestoda. - Parasitic within the host; without cilia or digestive cavity: Tania.

Branch V. NEMATHELMINTHES. - Body cylindrical, pointed at each end, cuticle tough, body cavity present.

CLASS I. Nematoda. - Characters of the branch: Trichina.

Branch VI. TROCHELMINTHES.- Microscopic but multicellular, with body cavity, digestive and nervous systems, body bearing cilia in rings or scattered over the surface.

CLASS I. Rotifera. - Cilia on a retractile disk at anterior end: Brachionus.

Branch VII. MOLLUSCOIDA. — Having a lophophore or tentacle bearing ridge at anterior end of body.

CLASS I. Polyzoa. - Forming colonies, minute, fixed: Flustra.

CLASS II. Brachiopoda. — Body inclosed in two-valved shell; no gills; two ciliated arms; fixed; marine: Terebratula.
Branch VIII. ECHINODERMATA. - Radiate Metazoa, with distinct alimentary canal and well-
developed nervous system; body walls secreting calcareous plates; parts in multiple of five.
CLASS I. Asteroidea. — Body star-shaped; free; mouth underneath; moving by suckers under the hollow lobes of the
body: Asterias.

CLASS II. Ophiuroidea. - Body star-shaped; free; mouth underneath; moving by long slender arms: Ophiura.

CLASS III. Echinoidea. — Body inclosed in a spinous shell; free, moving by suckers; mouth spherical: Arbacia. underneath, with five teeth;

flat: Clypeaster.

CLASS IV. Holothuroidea. - Body cylindrical and soft; free, moving by suckers; mouth in front, surrounded by tentacles: Pentacta.

CLASS V. Crinoidea. — Body cup-shaped; mouth uppermost: Pentacrinus.

Branch IX. ANNULATA. - Soft body generally divided externally into a number of rings; no jointed appendages.

CLASS I. Chatopoda. -Body round, segments numerous, similar, and ( bristles numerous: Nereis.

bearing horny bristles;

CLASS II. Hirudinea. - Body flat, with suckers at ends: Hirudo.

bristles few on each segment: Lumbricus.

Branch X. ARTHROPODA. Metazoa, usually with definite number of segments and jointed appendages.

CLASS

§ 1. Water-breathing.

I. Crustacea. Having gills and more than eight jointed legs; four antenn

Order 1. PHYLLOPODA.

antennæ.
Very small; body segmented and bearing cephalic shield: Daphnia.
Minute; unsegmented body inclosed in bivalve shell: Cypris.
Small; body segmented and without dorsal shell: Cyclops.
CIRRIPEDIA. Fixed; shelly covering; feathery "arms": Balanus.

Order 2. OSTRACODA.

Order 3. Order 4.

COPEPODA.

Order 5. DECAPODA. - Shell of mingled lime and chitin; ten-footed; large: Cambarus.

Order 6. ARTHROSTRACA. -Thorax consisting usually of only six or seven segments; eyes sessile; small: Oniscus.

§ 2. Air-breathing.

CLASS II. Onycophora.- Body soft, cylindrical, unsegmented; legs soft, unjointed: Peripatus.

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