SOME NEW DEVON IC FOSSILS 203. 



The umbonal teeth are strongly developed in the left valve as a 

 set of three oblique ridges, behind them being a strong oblique 

 ridge. What may prove to be the right valve of the species has a 

 more convex surface, strong anterior muscle scar and teeth to cor- 

 respond with the sockets of the other valve. 



This species is like but much more oblique than the P. foil- 

 manni Freeh and P. 1 a e v is Goldfuss of the Coblentzian. 



Lower Devonic. Webster lake, north side, J /\ mile east of Telos 

 canal and Matagamon lake, on east side i mile above dam, Me. 



Pterinea chapmani no v. 



A large left valve has the beak almost terminal, a long straight 

 hinge, lateral teeth not visible but umbonal teeth sharply defined ; 

 posterior wing narrow and not extended, anterior wing very small ; 

 anterior slope abrupt, almost vertical ; umbo narrow elevated, the 



Pterinea chapmani 



general surface of the valve broadly convex ; outline oblique. The 

 surface carries faint radial riblets, which are obsolete on the 

 anterior slope. 



The species differs from any of its associates in its obliquity, 

 abrupt anterior slope, abbreviated anterior wing and short posterior 

 extension. 



Lower Devonic. Edmunds Hill, Chapman Plantation, Me. 



Pterinea edmundi now 



The distinguishing marks of this species are found in its orna- 

 ment and variable outline. In aspect it approaches very closely 

 the P. r a d i a 1 i s from Presque Isle stream but its left valve is 

 sometimes more oblique, sometimes more erect, its umbonal con- 

 vexity less marked. Its sculpture consists of coarse flattened ribs 

 which are more or less irregularly interspersed with ribs of smaller 

 size; on the anterior slope these gradually disappear leaving the 



