CAMBllO SILURIAN MICRO-PALAEONTOLOGY. 17 



Amplexoi'ORA Canadensis. (N. Sp.) 

 Plate IV., figs. %2d. 



Zoarium iiimoso, consisting of stout, sub-cylindrical, somewhat coni- 

 prosscd branches, measuring from 20 to 25 mm. in their greatest diameter. 

 Surface smooth and quite destitute of monticules. C/dl-aportures poly- 

 gonal, nearly equal in size, about three and a half occupying the width of 

 1 mm. 



In tangential sections the cell- walls are seen to bo moderately thick, 

 and to be provided at their angles of junction with spiniform tubuli of 

 medium size. 



Longitudinal sections show that the tubes have moderately thin walls 

 in the axial region, and that they are provided with very numerous 

 horizontal, slightly curved diaphragms, three or four of which occupy a 

 space equal to a tube diameter; these diaphragms sometimes coalesce. 

 Towards the periphery the proper wall of the tubes is considerably thick- 

 ened by an investment of light coloured sclerenchyma of fibrous texture. 



This species may bo separated from Amplexopora superba, Poord, which 

 is its nearest ally, by the absence of monticules, and by its very abundant 

 horizontal diaphragms. 



Locality and Formation. — St. Joseph laland, Like Tfuron, Black River 

 Formation ; Joliette, Quo. Trenton Formation. 



Collectors.—^, C. Weston, H. M. Ami. 



Amplexopora discoidea, Nicholson, Sp. 



Moniiculipora {Monotrypa) discoidea^ James. "The gonu3 Monticulipora," 

 p. 193, Plate IV.; ligs. 3;-3^ 1881. 



Locality and Formation. — Ottawa City. Trenton Formation. 

 Collector. — Walter E. Billings. 



Batostoma, U I rich. 



*' Irregularly ramose, with a large basal expansion, by means of which 



the zoarium is attached to foreign bodies. (JcU-aperturcs in the outer 



portion of the branches irregularly ovate or circular, and surrounded by a 



distinct ring-like wall. Interstitial tubes more or less numerous, very 



irregular in shape and size. Spiniform tubuli numerous and well 



developed." Black River, Trenton and Cincinnati. (E. O. Ulrlcli, Journ, 



Cincinnati Soc. Nat. Hist.. Vol. V., p. 154, 1882.) 

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