OF Till: CYSTIC ENTOZOA. 101 



reproductive organs. The pyriform sac always contains highly 

 refractive oil-like globules, but larger than those in the chyle 

 receptacle. The two larger globular masses are very constant, 

 and as well as the two smaller contain a mass of particles appa- 

 rently 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 pyri- 

 form sac. Whether these convoluted bodies be ovaries or con- 

 voluted oviducts, and the pyriform sac a uterus ; or whether the 

 former be the testes, and the latter the female organ, as in the 

 arrangement 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 compara- 

 tively dense integument of this part of the animal. 



This Distoma possesses a vascular system forming a network 

 throughout the body. The two principal trunks, as in the other 

 genera, passing along the sides of the body and being most ap- 

 parent at its posterior third. 



I. ACEPHALOCYSTIS. 



Completely buried in the textures of the infested animal ; young 

 only consisting of three membranes ; adult of four, the external one 

 belonging originally to the infested being. Nourished by epithelial 

 cells, which are contained in one of the membranes composing the sac. 

 Generated by means of cells arising from a germinal membrane. 

 Internal cavity filled with a watery fluid. 



1. Acephalocystis Simplex (Mihi). 



Parent sac quite transparent, with the membranes indivisible and the germinal cells very 

 minute. 



2. Acepltalocystis Monroii (Mild). 



Parent sac transparent and gelatinous ; germinal membrane intersected by membranous 

 bands, which form flattened compartments, in which are large cells containing unequal 

 numbers of young cells. Each of the young are marked with one or more dark spots. 



