DISTOMA OEASSUM. 



193 



D. Busldi, Lankester. 

 Bicrocoelium Busldi, Weinland. 



General and Specific Characters. — A trematode helminth varying from an inch and 

 a half to tliree inches in length, and having an average breadth of | of an inch ; 

 especially also characterized by its uniform and considerable thickness, combined with 

 the presence of a " double alimentary canal which is not branched ;" the body is pointed 

 in front, and obtusely rounded posteriorly; the integument being smooth and unarmed ; 

 the reproductive orifices placed immediately above the ventral sucker: the testes 

 form two bulky, lobed organs, situated below the ventral acetabulum, and disposed in 

 the middle line, one in front of the other ; the uterine folds occupy only the front part of 

 the body, the margins of which also display two vitelligene glands, one on either side of 

 the intestinal tube ; the excretory organ consists of a central trunk with divergmg 

 branches. 



TMs is a good species, and appropriately named ; for, although 

 Yon Siebold (in MuUer's " Archiv" for 1836, p. 234, and in his 

 " Lehrbuch," vol. i. p. 143) refers to a Distome infesting Hirundo 

 urbica under this title, he has given no description of the worm. 

 Diesing places Von Siebold' s D. crassum among his species inqui- 



Fia. 42.— Outline drawing oi Bistoma crassum, Busk ; the parts not actually visible, in the speci- 

 mens examined, being indicated by dotted fines ; a, oral sucker ; I, acetabulum ; c, reproduc- 

 tive papiUa ; d, uterine canal ; e, ovary ; /,/, testes ; g, g, g, g, Intestinal tubes ; h, aquiferous 

 or excretory canal. — Original. 



rendfB, and it is very probably identical with the D. maculosum of 

 Rudolphi. No other instance has occurred siace the original fourteen 



c c 



