SOME NEW DEVON IC FOSSILS 285 



ope Hall, Hamilton). The surface is crossed by fine and obscure 

 •concentric lines. On the interior the ventral valve bears flabellate 

 muscle scars but it is not known whether the scars of the dorsal 

 valve conform to those of Schizophoria. Specimens of this species 

 are easily confounded with those of Dal. 1 u c i a but the con- 

 tour of the two is exactly reversed. 



Dimensions. A normal specimen measures 18 mm in length 

 and 20. mm in width. 



Lower Devonic. Grande Greve, P. O. 



Orthostrophia canadensis now 



Valves subcircular w r ith a straight hinge ; in contour the 

 ventral valve is the shallower but bears a high median ridge, while 

 the deeper dorsal valve carries a broad and low median sinus. 

 Inside, the ventral valve has the muscular area concentrated pos- 



Orthostrophia canadensis 



teriorly into a single scar not more extensive than the single pedicle 

 scar in more typical orthids ; the dorsal valve has a thin erect car- 

 dinal process and four distinct adductor scars. 



The surface is marked by radial striae of unequal size. 



Lower Devonic. St Alban beds. The Grande Cavee, and Cape 

 Rosier Cove. This species is also known to occur in the Square 

 Lake limestone of Northern Maine. 



Dalmanella penouili now 



This is a small circular shell without median depression or ele- 

 vation but with an elevated ventral valve and high cardinal area, 

 simulating in this regard a Schuchertella but without the deltidium 



