332 ESSAY ON CLASSIFICATION. 



CL. 7. TURBELLARII. Onl. Rhabdocoeli, Dendrocoeli. 

 CL. 8. ROTATORII. Not subdivided into orders. 

 CL. 9. ANNTJLATI. Ord. Apodes and Cheetopodes. 



IV. MOLLUSCA. 



CL. 10. ACEPHALA. Ord. Tunicata, Brachiopoda, Lamellibranchia. 

 CL. 11. CEPHALOPHORA, Meek (Gasteropoda). Ord. Pteropoda, He- 



teropoda, Gasteropoda. 

 CL. 12. CEPHALOPODA. Not subdivided into orders. 



V. AllTIIHOPOPA. 



CL. 13. CRUSTACEA. Ord. Cirripedia, Siphonostoma, Lophyropoda, 



Phyllopoda, Poecilopoda, Lteniodipoda, Isopoda, Auiphipoda, 



Stomapoda, Decapoda, Myriapoda. 

 CL. 14. ARACHNIDA. Orders without names. 

 CL. 15. INSECTA. a. AMETABOLA. Ord. Aptera. b. HEMIMETABOLA. 



Ord. Hemiptera, Orthoptera. c. HOLOMETABOLA. Ord. 



Diptera, Lepidoptera, Llymenoptera, Strepsiptera, Neuro- 



ptera, aud Coleoptera. 



VERTEBRATA. 

 VI. VERTEBRATA. 



CL. 16. PISCES. Sub-classes: 1st. LEPTOC.ARDII. 2nd. MARSIPO- 

 BRANCUII. 3rd. ELASMOBRANCHII ; Ord. Holocephali, Pla- 

 giostomi. 4th. GANOIDEI ; Ord. Chrondrostei, Holostei. 

 5th. TELEOSTEI ; Ord. Acauthopteri, Anacanthini, Pharyn- 

 gognathi, Physostomi, Plectoguathi, Lophobranchii. 6th. 

 * DIPNOI. 



CL. 17. REPTILIA. Sub-classes: 1st. DIPNOA; Ord. Urodela, Ba- 

 trachia, Gyrunophiona. 2nd. MONOPNOA : a. Streptosty- 

 lica ; Ord. Ophidia, Sauria. b. Monimostylica ; Ord. Che- 

 Ionia CrOCOdila. ^^ e sub-divisions of the classes Pisces aud Rep- 

 I tilia are taken from the second edition, published in 



Pi 1ft AVES ^> 1^ 5 '*"{> G ' in which J. Miiller's arrangement of the 



| Fishes is adopted; that of the Reptiles is partly Stan- 



J nius' own The classes Aves and Mammalia, and 



CL. 19. MAMMALIA. the tirst volume of the second edition, are not yet out. 



The most original feature of the classification of von 

 Siebold is the adoption of the types Protozoa and Vermes, 

 in the sense in which they are limited here. The type 

 of Worms has grown out of the investigations of the hel- 

 minthologists, who, too exclusively engaged with the para- 

 sitic Worms, have overlooked their relations to the other 

 Articulata. On the other hand, the isolation in which 

 most entomologists have remained from the zoologists in 



