DB. T. S. C0BB6LD ON EISTTOZOA IK THE DOG. 291 



seemed altogether wanting. The practice of giving the viscera of 

 hares and rabbits to sporting dogs (which I have myself occasionally 

 witnessed in the field) will always ensure its prevalence in 

 this country. On five or six separate occasions I have reared this 

 tapeworm in dogs by the administration of the larvae (Ci/sticerctis 

 pisiformis) taken from recently killed rabbits. It is one of the 

 most easily reared of all the canine parasites, and, if due attention 

 be paid to the form and size of the head and its conspicuous 

 crown of hooks, cannot well be confounded with its allies. The 

 older helrainthologists are not trustworthy respecting the pre- 

 valence or otherwise of this species on the continent, since they 

 regarded several distinct forms as identical. Even Dujardin was 

 sceptical respecting the distinctive characters, severally, of TcBnia 

 serrata, T. marginata, and T. crassiceps (of the fox). 



16. Tcenia litterata. — This well-marked form is described by 

 Dr. Krabbe under the name of T. canis lagopodis ; but notwith- 

 standing the priority of Budolphi, I prefer the subsequent and 

 more distinctive nomenclature of Batsch, especially also because 

 the parasite is not by any means peculiar to the Arctic Fox {Canis 

 lagopus). Here we know nothing of this parasite ; and it may 

 be that it does not exist in England. On the other hand, its 

 general resemblance to Tcenia cucumerina may have caused it to 

 be overlooked. In seems from Krabbe's extended researches to 

 be altogether wanting in Denmark ; but in Iceland he found it in 

 21 of the 200 dogs which he there dissected. In the absence of 

 any definite knowledge respecting its larval source, it may be 

 assumed, as regards man, to rank amongst the so-called harmless 

 species. The joints (judging from the specimens kindly sent me 

 by Dr. Krabbe) have somewhat the appearance of those of Bo- 

 thriocephali, owing to the central and ventral disposition of the 

 reproductive organs. The orifices themselves, however, are not 

 actually visible, though probably present in thoroughly mature 

 segments. 



17. Tcenia ecMnococcus. — I come now to speak of a parasite of 

 the highest interest in relation to public health. Though fortu- 

 nately extremely rare in the adult condition, it is nevertheless 

 sufiiciently abundant to produce occasional fatal results by means 

 of its larvae. "What is the actual amount of human mortality thus 

 annually caused in this country it is not easy to say ; nevertheless 

 I know it to be something considerable ; and there is reason to 

 fear, in the absence of due precautions, that it may become much 

 greater. The larvae or hydatids are familiar to every hospital 



