Chap. III. ANATOMICAL SYSTEMS. 209 



The most originiil feature of the classification of von Sicl)ol(l 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 helminthologists, 

 who, too exclusively engaged with the parasitic Worms, have overlooked their rela- 

 tions to the other Articulata. On tlie other hand, the isolation in wliich most ento- 

 mologists have remained from the zoologists in general, has no doubt had its share in 

 preventing an earlier thorough comparison of the Worms and the larval conditions of 

 Insects, without which the identity of type of the Worms, Crustacea, and Insects 

 can hardly be correctly appreciated. Concerning the classes^ adopted by von Sie- 

 bold and Stannius, I have nothing to remark that has not been said already. 



CLASSIFICATION OF R. LEUCKART. 



The classification of Leuckart is compiled from the following work : Leuckart, (R.,) Ueber die Mor- 

 phologie und die Verwandtschaftsverhiiltnisse der wirbellosen Thiere, Braunschweig, 1848, 1 vol. 8vo. 



I. COELENTEKATA, Lkt. 



Cl. 1. Polypi. Ord. Anthozoa and Cylicozoa (Liicernaria.) 

 Cl. 2. A c a 1 e p h a e . Ord. Discopbonc and Ctenophorse. 



II. EcniNODERMATA, Lkt. 



Cl. 3. P e 1 m a t o z o a , Lkt. Ord. Cystidea and Crinoidea. 



Cl. 4. Actinozoa, Latr. Ord. Echinida and AsteriJa. 



Cl. 5. Scytodermata, Brrast. Ord. Holothuriffi and Sipunculida. 



III. Vermes. 



Cl. 6. Anenterati, Lkt. Ord. Cestodes and Acanthocephali. (Helrainthes, Burm.) 

 Cl. 7. Apodes, Lkt, Orrf. NL'mertini,Turbellarii,Trematodes, and Ilirudinei. (Trematodes, 5«n«.) 

 Cl. 8. Ciliati, Lkt. Ord. Bryozoa and Rotiferi. 



Cl. 9. A n n c 1 i d e s . Ord. Nematodes, Lumbricini, and Branchiati. (Annulati, Burm., excl. Ne- 

 mertinis et Hirudineis.) 



IV. Arthropoda. 



Cl. 10. Crustacea. Ord. Entomostraca (Neusticopoda Car.) and Malacostraca. 

 Cl. 11. Insecta. Ord. Myriapoda, Arachnida, (Accra, Latr.,) and Ilexapodiu 



V. IMollusca, Cuv. (Palliata, Nitzseh.) 



!-• in T' ■ i /^7^■l•/Tl.l. 1 Leucknrt is somewhat inclined to consider the Tuuicata 



Cl. 12. iunicata. Ord. AscidiiB (lethyes 



> not simply as a class, but even as another great type or branch, 

 Sav.) and SalpK (Thalidos Sav.) . ,. , „ , . 



^ ' ) mtcrmediate iR'tween Eclnnoileniis nnd Worms. 



Cl. 13. Acephala. Ord. Lamellibranchiata (Cormopoda Nitzseh, Pelecypoda Car.) and Bra- 



chiopoda. 

 Cl. 14. Gasteropoda. Ord. Ileterobranchia, (Pteropoda, Inferobranchia, and Tectibranchia.) 



D<'rniatuliranchia, (Oyniiiobranchia and Phlebenterata,) Heteropodsi, Ctenobrancliia, Pulnio- 



nata, and Cyclobraiu-hia. 

 Cl. 15. Cephalopoda. 

 VI. Vertebrata. (Not considered.) 



' Tlio names of the types, Protozoa and Vermes, are older ous ways for nearly half a centnn-, while that of Worms was first 

 than their limitation in the classification of Siebold. That of adopted by Linna;us, as a great division of the animal king- 

 Protozoa, first introduced by Goldfuss, has been used in vari- dom, but iu a totally different sense. 



27 



