ENtOZOA IN SEROUS CAVITIES. 123 



bably have the same effect upon these worms as upon 

 other entozoa. 



In some few cases the distomum hepaticum has 

 been found in the abdominal veins, into which it 

 has accidentally entered. 



Treutler has described two trematode worms, 

 which he observed in a wound communicating with 

 the anterior tibial artery; he considered these as 

 belonging to a distinct species, to which he gave the 

 name of Hexathyridium venarum, but it appears 

 highly probable that they were only the young of 

 the distomum hepaticum, or of the distomum lanceo- 

 latum. 



Chapter XVL 



GENEEAL REMARKS UPON THE ENTOZOA WHICH 

 EXIST IN NATURAL OR IN ADVENTITIOUS 

 SEROUS CAVITIES. 



The cavities which are invested by a serous mem- 

 brane may be affected by entozoa, as well as those 

 cavities which are provided with a mucous membrane. 

 These entozoa belong to the nematoid and to the 

 cestoid classes of worms ; the nematoid worms are 

 found only in animals, and especially in the horse. 



The cestoid entozoa which are found in the serous 

 cavities are vesicular worms which, in consequence 

 either of their number, or of their bulk, give rise to 

 marked derangements, or even to serious secondary 

 affections. 



The natural serous cavities are not all equally 



