26 University of Washington Publications in Geology [Vol. I 



PHAENOMYA NEW GENUS 

 Plate IX, Figures 6, 7, 8 



Type Phaenomya vaderensis n. sp. 



Description. Shell medium in size, trigonal in outline; equivalve; gibbous, 

 beaks high and| full ; anterior end rounded ; posterior end produced, a slight ridge 

 extends from the umbones to the posterior ventral margin ; right valve with a 

 tooth beneath the beak and in front of a wide and deep cartilage pit; in the left 

 valve there is a narrow, deep socket which extends anteriorly beneath the beak 

 and which lodges the tooth of the right valve; behind the socket and beneath the 

 beak there is a wide projecting, spatulate cartilage process which fits into the car- 

 tilage pit of the right valve; posterior ligamental area present, internal, widest 

 just behind the cartilage process; pallial sinus very slight; valves not gaping; 

 escutcheon impressed; lunule not present; shell smooth. 



The absence of the pallial sinus, the character of the tooth and socket of the 

 right valve and the general shape of shell are characters which are like Corbula, 

 the spatulate process of the left valve is like that of Mya; Phaenomya has in ad- 

 dition the deep groove or socket anterior to that process. 



This form is associated with a fresh water fauna which includes Goniobasis 

 olequahensis Arnold and Hannibal, Goniobasis hannibali n. sp., Anodonta arnoldi 

 n. sp., Hydrobia pontis n. sp. and Viviparus washing toniana Arnold and Hannibal. 



PHAENOMYA VADERENSIS n. sp. 

 Plate IX, Figures 6, 7, 8 



Description. Shell medium ; inequilateral, beaks situated about one-third of 

 the distance from the anterior end ; trigonal in outline, very convex ; beaks high 

 and prominent ; anterior end concave ; anterior margin sloping roundly to the 

 ventral margin ; ventral margin straight ; posterior end truncate, passing into the 

 ventral margin at a right angle and sloping to the beaks at an angle of 35 ; a 

 slight umbonal ridge extends from the beaks to the ventral margin ; surface 

 smooth except for the concentric lines of growth. 



Dimensions. Length 28 mm. ; height 20 mm. ; thickness 13 mm. 



Occurrence. At locality 315 (University of Washington Palaeontological 

 Collection) at the dam just below the railroad bridge at Vader on west bank of 

 Olequah Creek about one-third of a mile below its junction with Stillwater Creek, 

 Lewis County, Section 32, Township 11 North, Range 2 West. 



