JOURNAL AND PROCEEDINGS 



STROMATOPORID^. 



Read before the Geological Section^ May 2jrd, i8go, 

 BY A. E. WALKER. 



The subject for our consideration to-night will be those obscure 

 fossil forms belonging to the genus Stromatoporidse, of which there 

 are innumerable species, which have caused so much discussion to 

 all palaeontologists, in fact a perfect zoological stumbling block so 

 far. At first sight they much resemble Eozoon Canadense, but their 

 mode of fossilization and structure are remote \ they have be^ n re- 

 ferred to as corals, sponges, foraminafera, and even to hydracti- 

 niae, based probably on an imperfect acquaintance of the microsco- 

 pic structure of these forms. In the first place, it is extremely dif- 

 ficult to get these fossils so well preserved as to show their true 

 structure. They are dense, compact forms, and the slow process 

 of infiltration of the silicates or carbonates gives time for these de- 

 posits to recrystallize, and in a measure to destroy their delicate 

 structure. This is most particularly the case with those found in 

 the Niagara formation, and in the Guelph. These forms commence 

 in the lower Trenton, and follow up through the Hudson River, 

 Clinton, Niagara, Guelph, and through the Devonian. I am not 

 aware of their being found in the Carboniferous, as I have had no 

 opportunity of examining any of the later formations. 



In the year 1879 I sent a specimen to Sir J. W. Dawson, from 

 the corniferous limestone of Marble Head, Ohio, which was most 

 beautifully preserved ; the concentric laminae and pillars are in the 

 condition of opaque calcite, apparently retaining its minute structure, 

 and not affected by crystaUization ; the interspaces or chambers 

 are occupied by transparent calcite, permitting all the structure to 

 be very well seen, either on polished surfaces or transparent slices. 

 It was from this specimen that he published his report of the mi- 

 croscopic structure of stromatoporidse idea, which I place before you. 

 "It is evident that the animal matter of the stromatopora must have 

 occupied the chambers and interspaces, and must have extended 

 from chamber to chamber, also through the pores and hollow pillars. 



