103 



species which agrees very well with Prof. Hall's description, but it is de- 

 cidedly distinct from the one for which I now propose the name P. aperta. 

 This latter has over 100 radiating septa. 



Locality and Formation. Paquette Rapids, on the river Ottawa ; 

 Black River limestone. 



Collector. E. Billings. 



PETRAIA ANGULATA. (N. sp.) 



Fig. 90, a, 6. 



Description. Of this species we have only three small specimens. They 

 are irregularly conical, moderately curved, expanding from an acute point 

 to a width of seven lines at a height of about eight lines, acutely angu- 

 lated on the side opposite the con-cave curve. Surface with a few obscure 

 annulations of growth, and besides engirdled with numerous smaller ob- 

 scure lines, from four to six in one line. The cup appears to be about 

 four lines deep in a specimen eight lines in length. There appear to be 

 three or four septal striae on the outside in the width of one line. The 

 specimens being imbedded in stone, the number of the septa cannot be 

 ascertained. 



The distinctive character of this species consists in its acutely angular 

 shape. 



Locality and Formation. West end of Anticosti ; Hudson River group. 

 Collector. J. Richardson. 



PETRAIA PYGMEA. (N. sp.) 



Fig. 91. 



Fig. 92. 



Fig. 91. Petraia pygmea. A small slab of limestone with several specimens 



of this species, with some other fossils, imbedded in its surface. 

 92. P latuscula. a, Side view ; b, longitudinal section. 



