50 



ENTOZOA FOUND IN MAN. 



of an incli long. The head of the Dactylius is 

 obtuse, and truncated, and the mouth is orbicular. 

 The integument is armed with a number of sharp- 

 pointed spines, arranged in clusters of three or four, 

 and sometimes five, in longitudinal equidistant rows. 



Fig. 12.1 



Chapter Y. 

 ACANTHOTHECA. 



These are solitary animals, having a complete diges- 

 tive tube ; the mouth is situated 

 upon the inferior surface, and has a 

 pair of retractile hooks placed on 

 either side of it ; they have a dis- 

 tinct nervous system, and the sexes 

 are sej)arate. 



They present certain relations to 

 the Crustacea, and their embrvos 

 bear an evident analogy to those of 

 the Lerneidse, a species of Crustacea 

 which lives parasitically in fishes. 



Genus Pentastomum. 



In the worms comprised in this 

 genus the body is oblong, cylindrical, 

 or flattened, and sometimes attains 



1 Figure 12. Pentastomum Denticulatum considerably en- 

 larged. A small line placed at the side shows the natural length 

 of this entozoon. 



