160 WORMS INFESTING THE DOG. 



like Tcenia serrata, containing ova. These segments are oval 

 instead of square, as in Tcenia serrata, and have two marginal 

 sexual apertures, while the latter has only one. The colour varies 

 also, being milk-white in T. serrata, and pinkish-white in T. cucu- 

 merina. Of the development of this tape-worm nothing has yet 

 been discovered, but there is little doubt that it is very similar to 

 that which has already been described. Of course, this being the 

 case, the exact cystic worm with which it is identical cannot be 

 defined. 



The Tcenia echinococcus of Siebold is very small, being com- 

 posed of a head and only two or three segments, a,nd is developed 

 from the Echinococcus veterinorum infesting the liver and lungs 

 of the ruminants as well as the pig. This tape-worm is very rare 

 in comparison with the other two to which I have already alluded, 

 and practically its natural history is of no importance to the 

 courser. 



Besides the Tcenia, two intestinal worms are frequently found in 

 the dog, both belonging, in common with several other rare 

 parasites, to the nematoid order of entozoa, according to Rudolphi's 

 classification. These are usually known as the round-worm (Ascaris 

 marginata), and the maw- worm, which I cannot find described by 

 any of the foreign writers on the entozoa, but which is evidently a 

 thread-worm, and would then fall under the genus Oxyuris,' or 

 sharp tail. Unlike the Tcenice, which are androgynous, the nema- 

 toiclea require the contact of the male to fertilize the ova in 

 the female ovary. As soon as these are matured they are passed 

 into the intestine of the dog, and mixing with his fceces get into 



