104 



Description. Very small, elongate, conical, slender, slightly curved, 

 often in more than one direction ; radiating septa alternating in size, about 

 fourteen of the larger with an equal number of the smaller, at the margin 

 of individuals of the average size. Surface with a few obscure undulations 

 of growth. Cup moderately deep. 



Length, from 3 to 4 lines ; width of the cup at the margin, about 1 

 line ; depth of the cup, from to f of a line. 



This little species occurs in immense numbers in the Middle Silurian on 

 the Island of Anticosti. 



Locality and Formation. Challoupe River, Anticosti ; division 4, 

 Middle Silurian. 



Collector. J. Richardson. 



PETRAIA LATTJSCULA. (N. sp.) 



Fig. 92, a, b. 



Description. Corallum of medium size, short, turbinate, nearly straight 

 slightly curved towards the base, expanding to a width of from 8 to 10 

 lines in a length of from 5 to 8 lines, then becoming cylindrical or nearly 

 so. Cup rather deep. Radiating septa, as indicated by the external 

 markings, about 50. Surface with a few obscure undulations of growth ; 

 the longitudinal striae representing the septa are usually obscure, but in 

 some specimens distinctly marked. 



The most abundant specimens are from 5 to 10 lines in length, and from 

 8 to 10 lines in width at the margin. In one specimen 13 lines in length, 

 the width of the cup is 10 lines and the depth 5 lines. 



Locality and Formation. The Jumpers, Anticosti ; division 4. Mid- 

 dle Silurian. 



Collector. J. Richardson. 



