1906.1 



NATURAL SCIENCES OF PHILADELPHIA. 



213 



DESCRIPTION OF A NEW ATJSTEALIAN GLYCYMEKIS- 



BY HENRY A. PILSBRY, 



Glycymeris insignis n. sp. 



The shell is rounded-cuneate, the valves rather thick and strong, 

 inequilateral, the posterior outline being longer and subangular, the 

 anterior end rounded. The posterior dorsal slope is flat, and the 

 beaks project well above the dorsal outline of the valve-edges. The 



specimens are worn and without cuticle, white in the middle and ante- 

 riorly, pinkish orange near the posterior end. Sculpture of about 17 

 low rounded radial ribs parted by narrower intervals, and about six 

 strong broad but unequal concentric waves separated by deep con- 

 strictions. 



The waves and radial ribs are weak near the anterior end, and 

 wanting on the flat posterior slope. The hinge-line is very strongly 

 curved, the two sides at an angle of about 90 degrees to each other. 

 The hinge-plate is moderately wide, with 12 anterior and 11 posterior 

 teeth, three or four near the middle being very small and somewhat 

 irregular. There is a small triangular area or lozenge below the beaks, 

 sculptured en chevron with about six widely diverging grooves. The 

 basal margin is coarsely crenulate inside in correspondence with the 

 external ribs, and the concentric waves of the exterior are very weakly 

 indicated inside. 



