56 



Silurian Fossils of Ca?iada, 



tinct deflected margin, occupying from one-third to one-half tlie 

 length of the shell, appear to belong to this species. 



This species when the ears are broken away has exactly the 

 appearance of S. alternata, only that it is never more than half 

 the size. The characters of the hinge areas and teeth taken 

 together with the small size, and hinge ears are abundantly suffi- 

 cient to show that it is distinct from S. alternata. It is a longer 

 shell than S. nitens^ and is in general destitute of a deflected mar- 

 gin. It is smaller, thinner and less convex than S, Ceres, 



Locality and Formation. — Anticosti, in strata situated from 

 800 to 1000 feet above the base of the Middle Silurian, and 250 

 feet below the rocks containing Pentamerus oblongus. 



Collector, — J. Richardson. 



Stropiiomena Philomela. N. s. 



Tig. 4. 



Fig. 4. 

 5. 



Fig. 5. 



■Strophomena Philomela. 

 ■The same with a mesial fold. 



Description. — Shell rather large ; hinge line exceeding the 

 greatest width, forming short rounded ears ; sides gently convex, 

 converging towards each othier; front margin and angles regu- 

 larly rounded, sometimes with a projecting lobe in the middle. 

 Width on hinge line from eighteen to twenty four lines. Length 

 from two-thirds to four-fifths the width. 



In the ventral valve the umbo and depressions on each side are 

 well defined and exactly like those of the convex form of S. al- 

 ternaia. The visceral disc is moderately and broadly convex y 

 the deflected margin from one-fourth to one-third the whole 

 length of the shell, passing into the disc with a short rounded 

 curve. Dorsal valve with the curvature corresponding to that of 

 the ventral valve. 



The area of the ventral valve is a little more than half a line in 

 height at the foramen in a specimen two inches wide, and it in- 



