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INTRODUCTION 



found that the ova within their uterine tubes had 

 undergone development, and still contained living 

 embryos ; indeed, some of these hatched under the 

 microscope, and moved very actively in the preserv- 

 ing fluid. This is in no way surprising, because 

 even after several years of preservation in formalin 

 solution the embryos of other species of eelworms 

 (Ascaris equorum, A. marginata) have been found in 

 a living condition. 



Trematoda. — The Flukes {Trematoda) of snakes, 

 so far described, belong to the following genera : 

 Agamodistomum, Astiotrema, Brachylaimus, Cotylo- 

 tretus, Dicroccelium, Diplodiscus, Distoma, Halipegus, 

 Lecithodendrium, Metorchis, Opisthogonimus, Opis- 

 thorchis, Plagiorchis, Saphedera, Telorchis, Tetracotyle, 

 Zeugorchis. 



Cestoda. — Save a few larval forms (Cysticercoides, 

 Piestocystis, Sparganum), the known tapeworms 

 (Cestoda) of the Ophidia belong to the genera 

 Bothridium and Proteocephalus. 



Protozoa. — Numerous species of Hsemogregarines 

 have been described from snakes. As a rule the 

 forms seen in the peripheral blood are sporonts, the 

 schizogonic cycle occurring in the lungs. The 

 sporonts do not greatly alter their host cells ; they 

 are invariably doubled up within a more or less 

 thick capsule. Some species show a marked sexual 

 differentiation, others not. Tvypanosomes, Spiro- 

 echaudinnicz, and Plasmodidcz have also been de- 

 scribed from the blood of various snakes. 



