302 NOTES ON SOME CANADIAN INFUSORIA. 



perature, reappearing when the temperature increased, the ova 

 apparently not being affected at a temperature which de3troys the 

 adult animal. This is a well-known phenomenon, and is exemplified 

 by many of our Insects, which perish in the Fall, but whose eggs are 

 able to withstand the intense cold of Winter. These same remarks 

 apply to the Rotifer Philodina citrina, which was also present in 

 considerable numbers. A single Nematode worm, which I did not 

 identify, and several examples of a Planarian were seen, the latter 

 possessing a distinctly vacuolar parenchyma. Of the lower forms of 

 life many examples were observed : Arcellce, especially A. dentnta, 

 Amozbce, Actinophrys sol, and many Flagellata. Of these the Arcellce 

 persisted through all the changes, the Amcehce perished in low tem- 

 peratures, and Actinophrys, having only appeared lately, has not been 

 exposed to cold. 



With these preliminaries I shall now pass on to my observations 

 on certain Infusoria, which I regret are somewhat incomplete, owing 

 both to lack of sufficient time to perfect them, and more especially 

 to the want of the necessary literature, which, for efficient work, 

 shoud be continually at hand. 



Metopus, nov. spec. 



The genus Metopus was originated by Claparede and Lachmann 

 for the reception of a species formerly described by O. F. M tiller as 

 Trichoda sigmoides, and by Perty as an unknown form. It presents 

 many peculiarities, and has hitherto been frequently mistaken for 

 other forms ; Balbiani, for instance, mistaking it for the young form 

 of Spirostomum ambiguum. It has been described from several 

 localities in Europe, Claparede and Lachmann having found it at 

 Berlin, Englemann at Leipzig, Stein at Tharand and Niegmegk (very 

 numerous among Lemna polyorrhiza and trisulca), and Balbiani at 

 Paris, but as far as I can ascertain it has not yet been described from 

 America. 



The characters of the genus are thus given by Kent 1 : " Free- 

 swimming, highly elastic and changeable in shape, normally elongate, 

 oval, or fusiform, rounded at both extremities, cylindrical or only 

 slightly flattened; the anterior portion usually twisted obliquely 

 towards, and overlapping the left side of the ventral surface, sharply 



1 Manual of the Infusoria. London. 1882. 



