254 BURSARIES BALANTIIHUM. 



slit-like mouth, I am inclined to think that this species is simply 

 the very common Glaucoma scintillans, Ehrbg. 



Family BURSARIES. 



Heterotrichous Infusoria, with a sometimes oblique, sometimes straight, 

 peristomial cleft, which runs from the anterior end of the egg-shaped 

 body, generally on the right side of the ventral surface, as far as the 

 mouth, and is bordered only on the left side by the adoral cilia. 



Balantidium, Claparede and Lachmann. 



The body is egg-shaped, or rather longer, with ventral and dorsal 

 surface almost equally arched, anteriorly somewhat truncated, and pro- 

 vided with a peristomial region, which narrows posteriorly, and only 

 deviates slightly towards the right side of the ventral middle line. Tliis 

 asymmetrical condition is most striking in a state of rest, when the 

 peristome is bent together into a trough-like shape. The adoral cilia of 

 the left peristomial border differ only slightly in length and strength from 

 the cilia of the body. The mouth occupies the deepest part of the peri- 

 stomial region, and is continued into the interior by a short gullet. The 

 anus at the posterior end of the body is recognisable by the escape of 

 excrement. There arc generally two or three contractile vesicles. The 

 nucleus is of an oval or short ribbon-like form. All the species live 

 parasitically in the alimentary canal of the Vertebrata, especially in the 

 naked Amphibia. 



The genus Balantidium was instituted by Claparede and Lach- 

 mann, 1 for the reception of Ehrenberg's Bursaria entozoon, but was 

 erroneously credited with styliform cilia on both borders of the peri- 

 stomial notch. Stein was the first to recognise the true nature of 

 the peristome, and he increased the number of species, partly by new 

 discoveries, and partly by proving that the so-called Paramcecium coli 

 also belonged to this <zenus. 



Balantidium coli (Malmsten), Stein. 



Malmsteu,'* Archiv. f. pathol. Anat., p. 302, Bd. xii., 1857 (Paramcecium coli). 

 Leuckart, " Parasiten," first German edition, Bd. i., p. 146. 

 Stein, " Organismus der Infusorien," Abth. ii., p. 320. 



Ekeckrantz, Bidrag till kannedomen om de i menniskans tarmkanal forekommande 

 Infusorier," Nord. med. Ari'iv, No. 20, Bd. i., 1869. 



Wising, " Till kannedomen om Balantidium coli hos manniskan," ibid., Bd. iii., No. 3, 1871 . 



Infusoria with a short oval body (of - 07 to O'l mm. long by O'Oo to 

 07 mm. broad); the anterior end somewhat truncated, urith a very short 



1 Etudes, toe. cit. t t. i., p. 247. 



