﻿Animal Nature of Eozobn Canadense. 69 



III. STRUCTURAL AND BIOLOGICAL. 



In recent years I have been disposed to attach more 

 importance than formerly to the general form and 

 macroscospical characters of Eozoon. The earlier ex- 

 amples studied were, for the most part, imbedded in the 

 limestone in such a manner as to give little definite 

 information as to external form ; and at a later date, when 

 Sir William Logan employed one of his assistants, Mr. 

 Lowe, to quarry large specimens at Grenville and Cote St. 

 Pierre, the attempt was made to secure the most massive 

 blocks possible, in order to provide large slabs for showy 

 museum specimens. More recently, when collections 

 have been made from the eroded and crumbling surfaces 

 of the limestone in its wider exposures, it was found that 

 specimens of moderate size had been weathered out, and 

 could, either naturally or by treatment with acid, be 

 entirely separated from the matrix. Such specimens 

 sometimes showed, either on the surfaces or on the sides 

 of cavities and tubes penetrating the mass, a confluence 

 of the lamina?, constituting a porous cortex or limiting 

 structure. Specimens of this kind were figured in 1888,^ 

 and I was enabled to add to the characters of the species 

 that the original and proper form was " broadly turbinate 

 with a depression or cavity above, and occasionally with 

 oscula or pits penetrating the mass." The great flattened 

 masses thus seemed to represent confluent or overgrown 

 individuals, often contorted by the foldingr of the enclosing 

 beds. The openings or oscula penetrating some of the 

 larger specimens of Eozoon may perhaps be compared 

 with the central canal in the modern Carpenteiia. 



There are also in well-preserved specimens certain 

 constant properties of the calcite and serpentine layers. 

 The former are continuous, and connected at intervals, so 

 that if the siliceous filling of the chambers could be 



^ Geological Magazine, and Museum Memoir. 



