SPENCER NIAGARA FOSSILS. 595 



Those who regard Strot7iatopora as allied to Sponges consider 

 the laminiE and pillars as calcareous spicules cemented, and the 

 larger tubes as oscula — this last structure being the principal rea- 

 son for placing them with Sponges. The presence of spicules is 

 very doubtful. Principal Dawson states that he has detected 

 no spicules, and found that the larger perforations did not extend 

 to the true surface, besides being surrounded by a strong case. 

 This latter structure (the cased tubes) he regards as accidental 

 or as some coral like Syringopora, perforating the mass. If thess 

 forms be true Sponges, then the pores through the laminae are 

 inhalant pores for the animal, and the larger and more scattered 

 tubes are cxhalant oscula. In some species these larger tubes do 

 not occur over the surfaces of even larger size. If the weight of 

 the evidence is in favor of their alliance with Foraminifera, as it 

 appears to be, then the interlaminar spaces and the minute tubes 

 were filled with animal matter. The nearest analogues of more 

 modern times are the Loftusia and Parkeria (of Carpenter, 

 Brady, and G. M. Dawson), which are described as gigantic 

 arenaceous Forafnini/era. Of these two genera, Dr. G. M. Daw- 

 son has obtained one species in British Columbia as old as the 

 Carboniferous period. 



As noticed above, the large tubes do not occur in some speci- 

 mens even though of many square inches surface. Yet there are 

 other species where their occurrence is almost too regular to be 

 regarded as accidental. 



We will now notice briefly those Niagara species at Hamilton. 



Stromatopora concentrica (Goldfuss, 1826). 



Plate 6. Figs. 8 & 80, enlarged. 



In the Clinton and lower portions of the Niagara beds at Ham- 

 ilton we find spheroidal or irregular masses made up of concentric 

 laminae sometimes surrounding some foreign nucleus, or with a 

 crystalline interior. Always there is a more or less concretionary 

 appearance on the exterior surface. The laminae are connected 

 by pillars. The rectangular spaces are sometimes almost filled 

 or even obliterated by the thickening of the walls. No further 

 structure than the relative sizes of the cells and laminae (which 

 are without undulations) is apparent, owing to the crystalline 

 and compact structure of the limstone, which, about the organ- 



