606 PHILOSOPHY OF ZOOLOGY. 



Order II. 

 Habitation internal. 



The animals of this order were included by Linnaeus, in 

 his Vermes Intestina, and have more recently been denomi- 

 nated Entozoa by Rudolphi, who has successfully illus- 

 trated their physiological and systematical characters *. 

 They live and propagate within the bodies of other ani- 

 mals, inhabiting not only the intestines, but the vessels, 

 glands, and cellular substance. 



1st Tribe. 



Mouth and anus at the opposite extremities, with an ob- 

 vious intervening simple alimentary canal. 



This tribe forms the Nematoidea of Rudolphi, and the 

 Cavitaires of Cuviek. The form of the body is lengthen- 

 ed, neai'ly linear, round, transversely striated, and elastic. 

 In the integuments, transverse and longitudinal muscular 

 fibres may be perceived. In some species, the nervous col- 

 lar and double longitudinal filaments may be detected. 

 The mouth exhibits, in its lips, and surrounding papillae, 

 useful characters for classification. There is a distinct ab- 

 domen, containing the alimentary canal. There is no trace 

 in this or the follomng tribe, of aerating organs. The 

 sexes are distinct, and the organs placed posteriorly. The 

 following genera belong to this group : Filaria, Hamularia, 

 Trichocephalus, Oxyuris, Cucullanus, Ophiostoma, Asca- 

 ris, Strongylus, Liorhynchus, Prionoderma, and Shistura. 



2d Tribe. 



Mouth and anus not at the opposite extremities, nor is 

 there a distinct simple alimentary canal. 



The animals of this tribe constitute the Parenchyraateux 

 of CuviER. The body consists of cellular substance, 

 without a distinct abdomen, in which the organs of nutri- 

 tion and reproduction are imbedded. There is seldom an 



" " Entozoorum sive Vermium Instinalium Historia N.ituialis, auctore 

 C. A. Rudolphi," 2 vols. 8vo. Amst. 1808. 



