218 



ESSAY ON CLASSIFICATION 



ondary divisions which he calls sections, divisions, tribes, etc., before 

 he reaches the genera and species. With reference to the genera again, 

 we find marked discrepancies in different classes. Sometimes a genus 

 is to him an extensive group of species, widely differing one from the 

 other, and of such genera he speaks as "grands genres"; others are 

 limited in their extent, and contain homogeneous species without 

 farther subdivisions, while still others are subdivided into what he 

 calls sub-genera, and this is usually the case with his "great genera." 

 The gradation of divisions with Cuvier varies then with his classes, 

 some classes containing only genera and species, and neither orders 

 nor families nor any other subdivision. Others contain orders, fami- 

 lies, and genera, and besides these, a variety of subdivisions of the 

 most diversified extent and significance. This remarkable inequality 

 between all the divisions of Cuvier is, no doubt, partly owing to the 

 state of Zoology and of zoological museums at the time he wrote, and 

 to his determination to admit into his work only such representatives 

 of the animal kingdom as he could to a greater or less extent exam- 

 ine anatomically for himself; but it is also partly to be ascribed to his 

 conviction, often expressed, that there is no such uniformity or reg- 

 ular serial gradation among animals as many naturalists attempted 

 to introduce into their classifications. 



CLASSIFICATION OF LAMARCK^^ 



INVERTEBRATA. 

 I. Apathetic Animals. 

 Cl. 1. Infusoria. Ord. Nuda, Appendiculata. 

 Cl. 2. Polypi. Ord. Ciliati (Rotifera), Denudati (Hy- 



droids), Vaginati (Anthozoa and Bryozoa), and 



Natantes (Crinoids, and some Halcyonoids.) 

 Cl. 3. Radiaria. Ord. Mollia (Acalephae), Echinoderms 



(including Holothuriae and Actinias.) 

 Cl. 4. Tunicata. Ord. Bothryllaria (Compound Ascidi- 



ans), Ascidia (Simple Ascidians.) 

 Cl. 5. Vermes. Ord. MoUes and Rigiduli (Intestinal 



Worms and Gordius), Hispiduli (Nais), Epizoariae 



(Epizoa, Lernaeans.) 



Do not feel, and move 

 only by their excited irri- 

 tability. No brain, nor 

 elongated medullary mass; 

 no senses; forms varied; 

 rarely articulations. 



^Lamarck, Histoire naturelle des animaux sans vertebres ... (7 vols., Paris, 1815- 

 1822). A second edition with notes has been published by G(5rard P. Deshayes and 

 Milne-Edwards (10 vols., Paris, 1835-1843). For the successive modifications this classi- 

 fication has undergone see also Lamarck, Systeme des animaux sans vertebres . . . , 

 Philosophie zoologique ... (2 vols., Paris, 1809), and Extrait du Cours de Zoologie 

 du museum d'Histoire naturelle . . . (Paris, 1812). 



