Maryland Geological Survey 651 



Genus GONIOPHORA Phillips 

 GONIOPHORA HAMILTONENSIS Hall ' 



Plate LXV, Fig. 3 



Occurrence. — Jennings Formation, Parkhead Member. Williams 

 l?oad, 1352, 2 miles west of mouth of Town Creek, 1843; Town Creek, 

 1679, 1863; 2 miles west of Pawpaw, West Virginia, 1484 common; 21/2 

 miles above mouth of Sideling Hill Creek. Woodmont Membek, Ithaca 

 Fauna. Two miles west of Pawpaw, West Virginia, 1388. 



Collection. — ^Maryland Geological Survey. 



GONIOPHORA TRUNC^TA Hall 



Plate LXV, Figs. 4-6 



Ooniophora truncata Hall, 1885, Pal. of N. Y., vol. v, pt. i, sec. ii, p. 298, pi. 



xlii, figs. 9, 10; pi. xliv, figs. 1-5. 

 Ooniophora truncata Grabau and Shinier, 1909, N. Amer. Index Foss., vol. i, 



p. 519, fig. 699. 



Description: — "Shell of medium size, trapezoidal; length more than 

 twice the height; basal margin rounded in the anterior part, slightly 

 sinuate a little anterior to the middle and nearly straight or slightly curv- 

 ing to the postbasal extremity; posterior margin obliquely subtruncate, 

 slightly curving. Cardinal line short, straight. Anterior end short, 

 rounded, limited by an oblique sinus extending from the beak. Valves 

 convex below the umbonal ridge, gibbous in the umbonal region ; the area 

 above the umbonal ridge is flat or concave, or sometimes a little convex. 

 Beaks anterior, acute and incurved ; umbo prominent, angular. Umbonal 

 ridge strongly defined, acutely angular, extending to the postbasal ex- 

 tremity. Test of moderate thickness ; entire shell marked by fine, lamel- 

 lose, concentric strife, and that portion of the surface between the umbonal 

 ridge and the sinus is marked by strong, elevated, radiating strige, which 

 dominate the concentric striae. The test is raised into a crest along the 

 umbonal ridge, especially in the posterior half of its length. Anterior 

 muscular impression large and deep, situated close to the anterior margin, 



' For description and synonymy see page 271. 



