366 PALEONTOLOGY OF NEW YORK. 



seven coarse, often irregular plications, only a part of them reaching the 

 beak. 



The brachial valve is depressed-convex, with a conspicuous median fold, 

 grooved longitudinally and bounded by deep marginal depressions. The lateral 

 slopes are more convex than on the other valve, but are similarly plicated. 

 Surface of the valves usually without concentric growth lines. 



An average example has a length of 8 mm. and a greatest width of 7 mm. 



Hudson River group. Near Edgewood, Pike county, Missouri. 



Camarophoria rhomboidalis, sp. nov. 



PLATE LXU, FIGS. 2S-29. 



Shells of rather small size, subtriangular in outline with cardinal margins 

 extending for half the length of the valves. Pedicle-valve with apex scarcely 

 elevated, incurved, with deltidial plates usually concealed ; slightly convex 

 about the umbo, broadly depressed medially, forming a sinus which makes a 

 linguiform extension on the anterior margin. This sinus may bear one and 

 sometimes traces of two other low plications. The lateral slopes are smooth, 

 except at the margins, where there is faint evidence of one or two plications on 

 each. The brachial valve is convex and broadly rounded with abrupt umbo- 

 lateral slopes ; broad, low median fold, apparent only in the pallial region, and 

 bearing a median plication. Traces of two lateral plications are visible at the 

 margin of the valve, and these are somewhat more distinct on the surface than 

 on the opposite valve. Surface smooth or with fine concentric lines. The in- 

 terior structure of the shell is normal for this genus. 



Corniferous limestone. Cass county, Indiana. 



Parastrophia divergens, sp. nov. 



PLATE LXin, FIGS. 4-7. 



Shell of medium size with strongly convex brachial valve and depressed 

 convex, anteriorly concave pedicle-valve. The beak of the pedicle-valve is 

 erect, but not conspicuons ; from the gently convex umbo the surface slopes 



