324 ESSAY ON CLASSIFICATION. 



the Aggregata, the Brachiopoda, and the Bryozoa are also 

 only orders of the class Acephala. Before Echiuoderms 

 had been so extensively studied as of late, the separation 

 of the Echinoidea from Asteroidea might have seemed 

 justifiable ; at the present day it is totally inadmissible. 

 Even Leuckart, who considers the Echinoderms as a 

 distinct branch of the animal kingdom, insists upon the 

 necessity of uniting them as a natural group. As to the 

 Dimorphsea, they constitute a natural order of the class 

 Acalephse, which is generally known by the name of 

 Hydroids. 



CLASSIFICATION OF BURMEISTER. 



The following diagram is compiled from the author's Geschichte der 

 Schopfung ; Leipzig, 1843, 1 vol. 8vo. 



Type I. IRREGULAR ANIMALS. 



1st Sub- Type. CL. 1. INFUSORIA. 

 Type II. REGULAR ANIMALS. 



2nd Sub-Type. CL. 2. POLYPINA. Orel. Bryozoa, Anthozoa. 



3rd Sub-Type. CL. 3. RADIATA. Ord. Acalephae, Echinodermata, 



Scytodermata. 

 Type III. SYMMETRICAL ANIMALS. 



4th Sub-Type. CL. 4. MOLLUSCA. Ord. Perigymna (Tunicata); Cor- 

 mopoda (Acephala) ; Brachiopoda, Cephalophora 

 (Pteropoda and Gasteropoda); Cephalopoda. 

 5th Sub-type. ARTHROZOA. 



CL. 5. VERMES. Ord. Helminthes, Trematodes, and 



Annulati. 



CL. 6. CRUSTACEA. 1. OSTRACODERMA. Ord. Prothes- 

 mia (Cirripedia, Siphonostoma, and Rotatoria) ; As- 

 pidostraca (Entomostraca : Lophyropoda, Phyllopo- 

 da, Precilopoda, Trilobitee). 2. MALACOSTRACA. 

 Ord. Thoracostraca (Podophthalma) ; and Arthro- 

 straca (Edriophthaluia). 



CL. 7. ARACHNODA. Ord. Myriapoda, Arachnidse. 

 CL. 8. INSECTA. Ord. Rhynchota, Synistata, Antliata, 



Piezata, Glossata, Eleutherata. 

 6th Sub-type. OSTEOZOA. (Vertebrata.) 

 CL. 9. PISCES. 

 CL. 10. AMPHIBIA. 

 CL. 11. AYES. 

 CL. 12. MAMMALIA. 



