348 Parasites from the Zoological Gardens. 



up their abode in a variety of animals ; but, as a rule, appli- 

 cable to adult as well as to immature forms, each fluke has 

 a special liking for a particular host, though this ' ' natural 

 selection " is not always bounded by the consideration of the 

 species, the genus, the family, or even, in some few cases, the 

 order. 



Without further prelude, we proceed to notice the seven 

 flukes above referred to, in the following succession : — (1.) the 

 Distoma (Equate (Dujardin), from the alimentary canal of an 

 American barn owl (Strix ferlata) ; (2.) the Distoma minutum 

 (T.S.C), from the duodenum of an oyster-catcher (Hamatopus 

 ostralegus) ; (o.) the Distoma Boscii (T.S.C), from the lungs of 

 an American snake (Coluber) ; (4.) the Distoma coronarium 

 (T.S.C), from the intestine of an alligator (Alligator Missis- 

 sijppiensis) ; (5.) the Distoma ccmjunctum (T.S.C), from the 

 liver ducts of the American red fox (Cams fulvus) ; (6.) the 

 Distoma compactum (T.S.C), from the lungs of an Indian 

 ichneumon (Viverra mungos) ; (7.) the Bilharzia magna (T.S.C), 

 from the blood of the portal vein of the sooty monkey (Cer- 

 copithecus fuliginosus) . 



1. Distoma eeguale. — On the 8th of January, 1858, nine 

 examples were removed from the American owl. These little 

 parasites scarcely exceed a line in length, but they exhibit a 

 reddish-brown colour, in consquence of the numerous highly- 

 coloured and extremely minute eggs which are seen through 

 the transparent skin. 



2. Distoma minutum. — This species is principally remark- 

 able for its excessive minuteness, being barely discernible by 



the naked eye, and seldom exceeding the 

 1-1 00th of an inch in longitudinal diameter. 

 Its form is entirely different from the Dis- 

 toma brevicolle (Creplin), also described as 

 infesting this bird, and in our early examin- 

 ations we believe ourselves to have obtained 

 satisfactory evidences of its sexual maturity. 

 As, however, in so tiny a parasite, the appear- 

 ances of true reproductive organs and ova 

 may have misled us, w& suspend further de- 

 tails regarding it until we have again had an 

 opportunity of examining fresh specimens. 

 Those we originally discovered were procured 

 Distoma minutum. on the 19th of February, 1857. 



3. Distoma Boscii. — Though, like Bosc, 

 we found a great number of these Trematodes occupying the 

 cavity of the mouth, the larynx, and the lungs of an American 

 coluber, yet wo were not able to determine the precise speci<:< 

 of snake from which our parasites were taken. There is no 



