304 Canadian Record of Science. 



According to the researches of Froelich,* the methyl 

 groups in pseudo-cumidine, occupy the positions 2, 4 and 5, 

 the amido group being 1. There are thus only the positions 

 3 and 6 left for the ethyl groups to fill. The constitutional 

 formula for the base is therefore — 



NIL 



C 2 H 5 



CEL 



On the occurrence of Scolithus in Rocks of 

 the Ohazy Formation about Ottawa, Ontario. 



By Henry M. Ami, M.A., F.G.S. 



For years past, the occurrence of Scolithus in the lower 

 portion of the Cambro-Silurian or Ordovician strata, as it 

 is developed in the St. Lawrence and Ottawa Valleys, as 

 well as in the State of New York and elsewhere, was 

 almost invariably taken as the best indication of the pre- 

 sence of the Potsdam formation. 



Scolithus Canadensis, as described by the late Mr. E. 

 Billings in his first volume of the Palseozoic Fossils, p. 96, 

 was shewn to be eminently characteristic of the Potsdam 

 formation, its occurrence in a number of localities having 

 been recorded by him. Since then it has also been found 

 in rocks of the same horizon in various other localities, and 

 well recognized by geologists in general. 



The form Scolithus linearis, of Hall, is also referred to by 

 Mr. Billings, as occurring in the measures of the Potsdam, 

 as seen at L'Anse au Loup (Joe. cit. p. 2), but in no other 

 Cambrian or Ordovician formation have the remains of 

 Scolithus been recognised as yet, as far as the writer is 

 aware. 



* Berichte, xvii, 2573. 



