167 



valve is more tumid in the cardinal third, and rounded to the hinge, 

 where there is a low narrow ridge. A thread-like marginal fold is visible 

 in some parts of the margin. 



In this species there is no definite ocular tubercle, but a group of sev- 

 eral small tubercles on a slight elevation, occupy its place. The ocular 

 furrow is shallow, and close to the front of the hinge, and extends down- 

 ward opposite the anterior cardinal curve. 



Sculpture. The surface is covered with distinct pits, the spaces bet- 

 ween which become inosculating ridges, subparallel to the length of the 

 valve, but tending downward in the direction of the front of the valve ; 

 towards the hinge line the pitting is very minute. 



Size. Length 2 mm., width, 1 mm., depth of a valve nearly mm. 



Horizon and locality. Assise E. 1 c, Lower Etcheminian Fauna, at 

 Dugald brook, Escasonie, N.S. 



The sculpture, something like that of an Entonris or a Kirkbya but 

 finer, seperates this little species from the others. 



ESCASONA.* 



Can. Rec. Sci., vol. VIII. , 1902, p. 157. 



A few forms which cannot be referred to any described genus of the Genus 

 Eopalsezoic are present at two horizons in the Etcheminian. The typical Escasona - 

 form is in one of the highest beds of the Upper Etcheminian. It is short 

 and high and the slight eminence which appears to indicate the ocular tu- 

 bercle is close to the hinge. There is a long slope from the hinge toward 

 the middle of the valve ; it thus resembles Beyrichona ; but it does not 

 have the two strong furrows or pits near the hinge which characterize that 

 genus ; nor is the slope from the hinge so long. Though tumid in the 

 upper third of the valve, this form cannot be classed with Schmidtella, 

 because the slope in the upper third of the valve is not bent down 

 abruptly to the hinge, as in that genus ; and furthermore the outline of 

 the valve is that of Beyrichona and Bradorona, and not the round valve 

 of Schmidtella. I refer to this genus Beyrichona ovata of the Protolenus 

 fauna. The typical characters of the genus are in the first of the follow- 

 ing species, E. rutellum. 



ESCASONA RUTELLUM. PI. XIII, figS. 5 a to C. 



Can. Rec. Sci. Montreal, 1902, p. 458. 



A broad tumid species. Hinge two-thirds of the width of the valve. Escasona 

 Anterior cardinal curve obsolete ; posterior one-half of the length of the rutellum. 



* Named for the district of Escasonie in Cape Breton. 



