200 



NEW YORK STATE MUSEUM 



pressed or broadly sulcate. Umbo convex, narrow ; pallial region 

 sloping evenly downward and depressed. The surface sculpture 

 consists of well defined ribs, which are broad and sparse over the 

 median region where they usually carry one very small rib between 

 each two of the large ones. On the anterior slope and wing these 



Pterinopecten aroostooki 



ribs are smaller and also on the posterior slope and wing. Cancel- 

 lating lamellae cross the posterior wing and are visible in the sulci 

 of all the posterior surface of the valve. The left valves only are 

 known. 



Lower Devonic. Edmunds Hill, Chapman Plantation, Me. 



Limoptera rosieri nov. 

 This large and rather fine species has a flabellate outline with 

 umbones almost at the anterior end of the hinge. The hinge line 



«f 



Limoptera rosieri 



is very long and straight terminating posteriorly on the extreme 

 point of a very broad wing. The incurvature from this wing 



