26 On Flulccs. 



less so in the insectivorous moles and shrews, whilst at least three 

 distinct forms traverse the body of the unfortunate hedgehog. 

 As yet, none have been descried in the bears, properly so called, 

 but a single species is known to infest the closely allied badger. 

 Weasels and others are peculiarly liable to invasion, and the 

 same may be said of the amphibious seals. Among the her- 

 bage-loving rodents the squirrels and marmots are not usually 

 subjected to their attacks; but an Italian, named Targione 

 Tozzetti, is said to have detected the common liver-fluke in our 

 familiar Sciurus vulgaris. Even rats and mice are tolerably free 

 from trematodes, yet they harbour an immense variety of other 

 helminths. Flukes, like ourselves, rejoice in the flavour of 

 hares and rabbits, but they utterly repudiate a residence within 

 the body of the uninviting sloth. Our domesticated quadru- 

 peds, such as the horse and ass, are seldom troubled with their 

 presence ; but swine, on the other hand, are peculiarly annoyed 

 in this respect. Speaking generally, they are prevalent in all 

 ruminating herbivores, being grievously numerous in sheep 

 and cattle. 



Turning our attention to the feathered tribes, on the whole 

 it may be said that flukes are scarcely less abundant in birds 

 than in mammals. Hitherto we have not met with them either 

 in the flesh or viscera of pigeons, parrots, or even in the insect- 

 eating woodpeckers ; but, as might be expected, they are of re- 

 markably frequent occurrence in the alimentary canal of gulls, 

 herons, stalks, cranes, plovers, ducks, and other water birds. 



Flukes readily gain admission within the bodies of the cold- 

 blooded reptiles, and display an abiding partiality for the batra- 

 chian frogs and toads. In the water-loving salamanders they 

 occur less numerously; and in the saurian, chelonian, and ophi- 

 dian orders they are comparatively unknown. In members of 

 the piscine class they are almost always present, being markedly 

 plentiful in the stickleback, minnow, tench, perch, pope, bull- 

 head, mackarel, trout, salmon, ling, burbot, turbot, flounder, 

 lump-fish, sander, and dorado ; and still more* so in the perch, 

 pike, barbel, bream, eel, sole, sun-fish, and sturgeon. 



A contemplation of these cursorily recorded facts can 

 scarcely fail to suggest several peculiarities respecting the dis- 

 tribution of these creatures. That worthy helminthologist, 

 Carolus Asmund Eudolphi, to whose investigations we owe 

 so much, lcug ago remarked that the entozoa constituted a dis- 

 tinct fauna, or, in other words, a special collection of animals 

 whose country is the circumscribed region of the interior of 

 living beings. We may carry the simile further, and compare 

 each creature thus infested to an island home, whose parasitic 

 inhabitants having a tendency to roam, not unfrcquently visit 

 adjacent isles, that is, the bodies of other animals. Taking a 



