290 RECORD OF SCIENCE FOR 1887 AND 1888. 



Eozoon canadense has received some attention durin.i? the two years 

 under consideration. Sir William Dawson (CO, 09) has brought the dis- 

 cussion of the nature of Eozoon canadense n\) to the present time. In 

 the paper (09), issued by the Peter Kedpath Museum of McGill Uni- 

 versity, the author presents an exhaustive review of the characters of 

 jBJo2:oon, discusses the objections to its animal nature, and gives (on p. 

 91) a summary of the arguments in support of the animal nature of 

 Eozoon canadense, the chief points of which are as follows : 



''1. It occurs in masses in limestone rocks, just as Stromatoporse oc- 

 cur in the Pahneozoic limestone. 



<'2. While sometimes in confluent and shapeless sheets or masses, 

 it is, when in small or limited individuals, found to assume a regular 

 rounded, cylindrical or more frequently broadly turbinate form. 



"3. Microscopically it presents a regular lamination, the laminae 

 being confluent at intervals so as to form a network in the transverse 

 section. The lamin;e have tuberculated surfaces or casts of such tu- 

 berculated surfaces, giving an acervuliue appearance to those lamimie 

 which are supposed to be the casts of chambers. 



"4. The original calcareous lamiute are traversed by systems of 

 branching canals, now filled with various mineral substances, and in 

 some places coarse and in many others becoming a tine tubulated wall. 

 The typical form of these canals is cylindrical, but they are often flat- 

 tened, especially in the larger stems. 



"5. In some specimens, large vertical tubes or oscula may be seen to 

 penetrate the mass. 



" 6. On the sides of such tubes, and on the external surface the lam- 

 in fe subdivide and become confluent, thus forming a species of porous 

 epidermal layer or theca. 



'• 7. Fragments of Eozoon are found forming layers in the limestone, 

 showing that it was being broken up when the limestones were in pro- 

 cess of deposition. 



" 8. The great extent and regularity of the limestones show that they 

 were of marine origin, and they contain graphite, ai)atite, and obscure 

 organic ("?) fragments other than Eozoon. 



'' 9. The ordinary specimens of Eozoon are mineralized with hydrous 

 silicates (serpentine, etc.) in the same manner with Silurian and other 

 specimens filled with glauconite, etc. These hydrous silicates also oc- 

 cur in the same limestones in concretions, bands, etc., in such a manner 

 as to prove that they were deposited contemporaneously. 



" 10. In some cases the canals and chamberlets are filled with cal- 

 citean^l dolomite, in the manner of ordinary calcareous fossils, and this 

 filling can often be distinguished from the original calcareous wall by a 

 minutely granular or porous structure in the latter. 



"11. The specimens of Eozoon have been folded and faulted with the 

 containing limestones, showing that they are not products of any 8ut>- 

 sequent segregation. 



