4Q4 KNTOZOA. 



coition ensues as among other animals. We are then compelled to 

 believe, that they propagate their race by germs sufficiently minute 

 to be transmitted through the narrowest passages, and that frequently 

 those germs are contained in animals at birth. 



In the Intestinal worms we find neither tracheae, nor any other 

 organ of respiration, and they must receive the influence of oxygen 

 through the medium of the animal they inhabit. They present no 

 trace of a true circulation, and we merely perceive vestiges of nerves 

 so extremely obscure, that many naturalists have doubted their ex- 

 istence *. 



When those characters are found united in an animal Avith a form 

 similar to that of this class, we place it here, although it may not in- 

 habit the interior of another species. 



The injury caused by worms to animals, in which they become ex- 

 cessively multiplied, is well known. The most efficacious agent for 

 destroying those of the alimentary canal seems to be animal oil mixed 

 with spirits of turpentine f . 



We will divide the Entozoa into two orders, which are perhaps 

 sufficiently different in organization to form two classes, if we had 

 the observations requisite to determine their limits. These orders 

 are the 



Entozoa Nematoidea, IhicL, 



Which have an intestinal canal floating in a distinct abdominal 

 cavity, a mouth and anus ; and the 



Entozoa Parenchymata|, 

 Where the parenchyma of the body contains obscurely terminated 

 viscera, most commonly resembling vascular ramifications, and some- 

 times not visible. 



ORDER I. 



NEMATOIDEA, Rud.§ 

 This order comprises those whose external skin, more or less fur- 

 nished with muscular fibres, and usually striated transversely, contains 

 an abdominal cavity in which is a distinct intestinal canal, extending 



* For the anotomy of these Worms, besides the Entozoa of Rudolphi, see the Mem. 

 of M. Otto, Soc. Nat. Berl., 1816, and the work of M. J. Cloquet. 



t See Chabert, Traits des Maladies Vermineuses, and Rudolphi, I, p. 493. 



X They comprise the four last orders of Rudolphi. 



§ This order, -with the exception of two the last genera, constitutes the Entomo- 

 ZAJRES Apodks OxYCEi'HALiiS of M. dc Blainvillc. 



