90 INTRODUCTION. 



SUB-KINGDOM V,— ANNULOSA, 

 DIVISION I.— SCOLECIDA. 



CLASS I.— PLATYELMIA (Flat-worms). 



i. T^eniada .... Tce?iia. No fossil forms. 



2. TREMATODA . . . Distoma. No fossil forms. 



3. Turbellaria . . . Planaria, Nemertes. No fossil forms. 



CLASS II.— NEMATELMIA (Round- worms). 



1. Acanthocephala . . Echinorhynchus. No fossil forms. 



2. Gordiacea . . . Gordins. No fossil forms. 



3. Nematoidea . . . Ascaris. No fossil forms. 



CLASS III.— ROTIFERA (ROTATORIA). 



The Wheel-animalcules are wholly unknown in the fossil condition. 



DIVISION II.— ANARTHROPODA. 



CLASS I.— GEPHYREA (Spoon-worms). 



With the very doubtful exception of the Jurassic genus Epiirac/iys, no represen- 

 tative of the Spoon-worms is known in the fossil condition. Well-known 

 recent genera are Sipuncuhis and Echhwits. 



CLASS II.— MYZOSTOMIDA. 



The type-genus is Myzostoma. (Recent and fossil). 



CLASS III.— ANNELIDA (Ringed-worms). 



1. Hirudinea . . . Sanguisuga, Clepsine. No fossil forms. 



2. Oligoch^ta . . . Lumbricus (Earth-worm). Not certainly 



known in the fossil condition. 



3. Polych^ta. 



a. Tubicola . . . Serpula, Spirorbis, * Comulites. 



b. Errantia . . . Nereis, Aphrodite, *Eunicites, * Arabellites . 



CLASS IV.— CHiETOGNATHA (Arrow-worms). 



This class comprises the single recent genus Sagitta, and has no 

 fossil representatives. 



DIVISION III,— ARTHROPODA. 

 CLASS I. -CRUSTACEA. 



Sub-class I. — Anchoracephala. 



1. Cirripedia . . . Lepas (Barnacle), Balamis (Acorn - shell), 



* Turrilepas. 



2. Rhizocephala . . . Peltogaster, Sacailina. No fossil forms. 



Sub-class II. — Entomostraca. 



1. Ostracoda . . . Cypris, Cypridina,* Beyrichia,* Primitia. 



2. Copepoda .... Cyclops^ Lemcea, Argnlus. No fossil forms. 



3. Cladocera . . . Daphnia. No fossil forms. 



4. PHYLLOPODA . . . Apus, Estheria, Branchipus. 



5. Phyllocarida . . Nebalia, * Hymeuocaris, * ' Ceraiiocaris, *Dis- 



cinocaris. 



