CLASSIFICATION OF THE ANIMAL KINGDOM. 8/ 



menkreis "), apart from all considerations relating to their range in 

 time and in space." Such a series may be connected by transitional 

 forms with other morphological groups without losing its claim to be 

 considered as constituting a " species," provided the series does not 

 shade off in all directions into allied groups. 



The following synoptical table gives the leading divisions of the 

 animal kingdom, with typical examples of each. Forms marked 

 with an asterisk are extinct, and are only known in the fossil 

 condition : — 



TABULAR VIEW OF THE CHIEF DIVISIONS OF THE 

 ANIMAL KINGDOM. 



INVERTEBRATE ANIMALS. 



SUB-KINGDOM I. — PROTOZOA. 



CLASS I.— GREGARINIDA. 



Gregarina, Monocystis. No fossil forms of this class exist. 



CLASS II.— RHIZOPODA. 



1. Monera .... Protamceba. No fossil forms. 



2. Amgebea .... Amoeba, Difflxigia, Arcella. No fossil forms. 



3. FORAMINIFERA . . . Gromia, Biloculina, Sacccu)imina, Lituola, 



Textularia, Lagena, Globigeriua, Rotalia, 



* Orbitoides, Nummulina. 



4. RADIOLARIA . . . Thalassicolla, Acanthometra, Podocyrtis, Eitcyr- 



tidium. 



5. Heliozoa .... Actinophrys, Actinospharium. No fossil 



forms. 



CLASS III.— INFUSORIA. 



1. Ciliata .... Paramecium. No fossil forms. 



2. Suctoria .... Acineta. No fossil forms. 



3. Flagellata . . . Codosiga. No fossil forms. 



4. Cilio-flagellata . . Ceratium, Peridinium. Doubtful fossil repre- 



sentatives are known. 



SUB-KINGDOM II,— PORIFERA. 



CLASS I.— PLETH0SP0NGL2:. 



1. Myxospoxgle . . . Halisarca. No fossil forms. 



2. Ceratospoxgle . . . Euspongia. Fossil representatives of doubtful 



occurrence. 



3. MONACTINELLID^ . . Spongilla, Cliona, * Scoliorhaphis. 



4. Tetractinellid.-E . . Tethya, Geodia, Pachastrella, * Tethyopsis. 



5. Lithistid^E . . . Discodermia, Corallistes, * Chenendopora, 



* Dory derma, * A itlocopium, * Siphonia , 



* jferea, * A stylospongia . 



6. HexactinelliD/E . . Holtenia, Euplectella, Hyalonema, * Ventri- 



culites, * Protospongia, * Caloptychhim. 



