INTKODUCTION. 11 



whole. For if we adopt the name Pehnatozoa, we cannot retain the name 

 Crinoidea, whicli. according to Leuckart, would include the Brachiate Cri- 

 noids as well as the Blastoids, in opjiosition to the C^stids, — a most un- 

 natural subdivision. We do not express our views of the affinities of 

 Crinoids {scum hitiore) by immediately adopting a different primary sub- 

 division of the Pehnatozoa, and suggesting, as is done by Carpenter, that 

 these subdivisions should be Classes of the Branch of Echinoderms, — a 

 proceeding which, under the ordinary rules of nonaenclature, would at once 

 do away with the Pelmatozoa as defined by Leuckart. 



In sutforestino; the name Actinozoa of Latreille for the Echini and 



CO O 



Asterida, Leuckart exemplifies admirably the confusion consequent upon 

 the practice of applving the nomenclature of the larger subdivisions of 

 the animal kingdom to smaller groups, thus narrowing the limits of the 

 definition. The expansion of these limits to admit new members is not 

 so objectionable. 



Latreille in 1824 in his '' Esquisse d'une Distribution generale du Regne 

 Animal," (p. 18.) proposed the name Actinozoa, or "animaux rayonnes, . . . 

 avec trois classes, les Holothurites, les Echinodermes, et les Tuniciers," in 

 opposition to the Entozoa ! In his " Families naturelles du Regne Animal," 

 Paris, 1825, Latreille's Actinozoa form the second Branch of his Acephala, 

 and they include the Tunicates (the third Class of the second Branch), 

 the fourth Class, the Holothurida, and the fifth Class, the Echinoderma. 

 So that Leuckart's limitation of Latreille's name to the Echini and Star- 

 fishes only is very misleading, as Latreille included in his Starfishes the 

 ComatuliB, though he makes a fiimily of the genus Encrinus, the "Caules- 

 centia," and still further includes in his Actinozoa the Helianthoidea as a 

 sixth Class, including the Lucernariae, Actiniae, and Zoanthus. 



The confusion is still further increased from the geiieral use by English 

 writers of the Actinozoa as limited by Huxley,* in which he includes the 

 Polyps and Ctenophora? ; so that the Actinozoa as imderstood by most 

 English writers have but little in common with the Actinozoa as originally 

 defined by Latreille, and nothing whatever with the Actinozoa of Latreille 

 as limited by Leuckart. 



It is undoubtedly true that Leuckart was the first to contrast the Crinoids 

 or Pelmatozoa with the Holothurians and Actinozoa, but he did not expre.ss 



* Iluxley, T. II., Lectures on the Elements of Comparative Anatomy, London, ISfit. Lectures 

 I.-VI. Ou the Classification of Animals (originally published iu the Medical Times and Gazette). 



