^gS TRANS. ST. LOUIS ACAD. SCIENCE. 



ism, is often silicified. It is highly probable that this Niagara 

 form is referrible to ^. concentrica. 



Genus CAUNOPORA (Phillips, 1841). 



•' The typical species is ' amorphous,' composed of concentric 

 or nearly plane masses perforated by flexuous or vermiform small 

 tubuli and by larger straight subparallel or radiating open tubes^ 

 persistent through the mass. This definition includes those spe- 

 cies with simple tubes giving origin to radiating tubuli passing 

 through the thickened lamin.-e." 



Such is the description of this genus as defined by Dr. Dawson 

 in the Qiiarterly Journal of the Geological Society (Feb., 1879). 

 As that distinguished geologist also remarks, the specimens 

 both of this genus and Ccenostotna (Winchell, 1867) bear much 

 closer analogies to Sponges than those of the typical Stromato- 

 pora^ "as the vertical tubes may be taken for osczila, and the ex- 

 tremities of the fine tubes as incurvent pores." But the " solidity 

 of the calcareous walls and the supplemental thickening are at va- 

 riance with such views." In the paper from which the above is 

 quoted, the author has been obliged to reverse the generic names 

 " Caunopora" and "• Coenostoma" as used by Hall. 



To this genus, Caunopora — at least two species of organisms 

 belonging to the Upper Silurian system — should be placed. 



Caunopora walkeri, nov. sp. 



Plate 6. Figs. i» & 9a. 



Parasitic, incrusting other bodies (in this case Favositcs, in a 

 hemispherical form thinning out at margins) to a depth of two 

 centimetres. Laminae thin and obscure with chambers entirely 

 filled with supplemental matter, only occasionally traversed by 

 short tortuous horizontal canaliculi, connected with the vertical 

 tubes. Vertical pillars connecting laminae removed or obscured 

 by the filling, but with numerous connecting pores apparent and 

 filled with matter diflferent from that of the rest of the mass. 



The organism is traversed by irregularly situated vertical tube& 

 producing orifices on the surface of about one-half millimetre diam- 

 eter, and scattered over the surface at from 2 to 4 mm. apart. In 

 some places these seem to be surrounded by walls. The con- 

 necting pores are crowded together and are apparently situated 



