THE CYSTIC ENTOZOA. 5<»1 



human os uteri into the vagina. This organ, in its relations 

 and structure, appears to be tlie analogue of the cavity 

 described by Professor Owen, as opening into the posterior 

 orifice of Distoma clavaium, and supposed by him to be a 

 resjjirator}' organ. 



A pyriform sac, connnunicating with the exterior by the 

 pore in front of tlie acetabuhim, and two large, with occa- 

 sionally two smaller gh^bular masses, would a])pear to be the 

 analogues of the reproductive organs. Tiio ])yriform sac 

 always contains highly refractive oil-like globules, but larger 

 than those in the chyle-receptacle. The two larger globular 

 masses are ver}^ constant, and, as well as the two smalh-r, 

 contain a mass of particles apparently nucleated. From the 

 two larger, I have only been able to see faint traces of what 

 appeared to be ducts passing in the direction of the smaller 

 masses, and towards the neck of the p}Tiform sac. Wliether 

 these convoluted bodies be ovaries or convoluted oviducts, 

 and the pyriform sac a uterus ; or whether the former be 

 the testes, and the latter the female organ, as in the aiTange- 

 ment described in the other Distomas ; or whether they be 

 reproductive organs at all, I have failed in satisfying myself, 

 in consequence of the delicacy of their texture, and the com- 

 paratively dense integument of this part of the animal. 



This Distoma possesses a vascular system forming a net- 

 work throughout the body. Tlie two principal tnmks, as in 

 the other genera, passing along the sides of the l)ody and 

 being most apparent at its posterior third. 



I. ACEPHALOCYSTIS. 



n' Comph'tcly burifil in tin- tixtures of tin- infested animal ; 

 young only consisting of three membranes ; adult «»f four, the 

 external one lM»l<>n;^ang oriji^nally to the infested being. 

 Nourislied by epithelial cells, which are contained in one of the 



