﻿2 Caymdian Record of Science. 



Two keels extend the entire length of each division, and 

 between them is a single row of perforations piercing the 

 zoariuni in a direction at right angles to the plane in 

 which it lies ; these perforations are circular, oval or 

 oblong at the surface, from 0.5 to 1 mm. in diameter 

 or length, and are separated by raised margins on a level 

 V7ith the keels. On either side of the elevated central 

 portion of the divisions is a depressed marginal area 

 occupied l)y a row of circular or oval pores which vary in 

 •diameter or length from 0.2 to nearly 1 mm., and when 

 oval have the major axis at right angles to the direction 

 of the divisions. From six to twelve perforations occur in 

 a length of 1 cent, and from sixteen to forty pores in the 

 same distance. In transverse sections the perforations 

 are seen to extend through the thickness of the zoarium 

 and to be of the same width throughout their length, but 

 the pores after extending inward parallel to the direction 

 of the perforations for a distance nearly equal to the 

 thickness of the zoarium appear to enter the perforations 

 from either side by an abrupt turn. The connection of 

 the pores, however, with the perforations, if any, has not 

 been ascertained with any degree of certainty. 



The specimen figured was collected by the writer from 

 the Trenton limestone at Hull, P.Q., near Ottawa, in 1890. 

 It is calcareous and is preserved in a thin layer of black 

 shale lying on a dark grey limestone. Only one side of 

 the fossil has been seen, and at the centre of the disc the 

 surface is abraded and the structure obliterated. At a 

 later date Dr. H. M. Ami obtained a fossil, from the same 

 locality, which is thought by the writer to belong to the 

 ^ame species ; it does not show the details of structure 

 preserved in the first mentioned specimen, but in it 

 the thin edge of the organism is preserved showing 

 the circular outline. 



This organism appears to belong to the Polyzoa, but is 

 different from any genus known to the writer, nor is 



