CLASS V. 

 INTESTINAL WORMS (ENTOZOA) 1 . 



BY Intestinal Worms are understood worms that live in other ani- 

 mals, (not necessarily in their viscera) . Though not more correctly 

 in point of language, they might, perhaps, be better named Internal 

 Worms, which would be a literal translation of the word Entozoa. 

 This class is by no means natural, for the animals included in it not 

 only differ remarkably from each other in external form, but also 

 in internal structure. The efforts that have been made hitherto to dis- 

 tribute the different orders and families of the Entozoa amongst the 

 different classes of invertebrate animals have not been satisfactory. 

 In this, as in so many other attempts to determine the affinities of 

 animals, a certain external resemblance has been mistaken for 

 correspondence of internal structure and of type of organisation, by 

 which alone true affinities can be established. An unprejudiced 

 inquirer will scarcely attach more value to a comparison of EcMno- 

 rhynchua with Sipunculus, of Cysticercus with v bladder-bearing 

 Acalephs, &c. than to a comparison of bats with birds. Consequently 

 we are compelled to retain the class Entozoa, however we acknow- 



1 Compare on this class : 



C. A. RUDOLPHI, Entozoorum sive Vermium intestinalium Historia naturalis, m. 

 Tomi, c. tab. sen. Amstelaedami, 1808 10, 8vo. 



C. A. RUDOLPHI, Entozoorum Synopsis, cui accedunt Mantissa duplex et indices 

 locupletissimi, c. tab. III. aen. Berolini, 1819, 8vo. 



DR.BREMSER, Ueber lebende Wurmer im lebenden M enschen. Mit iv. ilium. Kupfert. 

 Wien, 1819, 4to. 



BREMSERI Icones Helminthum. in. Fasciculi. Viennae, 1823, folio. 



J. CLOQUET, Anatomic des Vers intestinaux Ascaride lombricoide et Echinorynque 

 ggant. Avec 8 pi. Paris, 1824, 4to. 



A. VON NORDMANN, MikrograpliiscJie Beitrdge zur Naturgescliickte der wirbellosen 

 Thiere. Istes Heft. Mit 10 Kupfertaf. Berlin, 1832, 4 to. 



F. DUJARDIN, Histoire naturelle des HelmintJies ou vers intestinaux. Avec 12 pi. 

 Paris, 1845, 8vo. 



Other important, more special works of MEHLIS, CREPLIN, LEUCKART, C. TH. VON 

 SIEBOLD, will be indicated further forward. See also the article Entozoa of OWEN in 

 TODD'S Cyclopaedia n. pp. no 144 (1837). 



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