250 Systematic Paleontology — Middle Devonian 



Superfamily PTERIACEA 

 Family PTERINEIDAE 



Genus PTERINEA Goldfuss 



Pterinea flabellum (Conrad) 

 Plate XXIX, Figs. 1-4 



Avicula flabella Conrad, 1842, Jour. Acad. Nat. Sci., Phila., voL viii, p. 238, 



pi. xii, fig. 8. 

 Avicula flaltella Vanuxem, 1843, Geol. N. Y., pt. iii, p. 152, fig. 3. 

 Avicula flabella Rogers, 1858, Geol. Penna., vol. ii, p. 826, fig. 659. 

 Pterinea flahella Hall, 1884, Pal. N. Y., vol. v, pt. i, Lamellibranchiata i, p. 



93, pi. xiv, figs. 1-21; pi. xv, figs. 1, 4-6, 8-10; pi. Ixxxiii, figs. 11, 12. 

 Pterinea flabella Keyes, 1891, Johns Hopkins Univ. Circ, vol. xi, p. 29. 

 Pterinea flabellum Clarke, 1903, N. Y. State Mus., Bull. 65, p. 494. 

 Cornellites flabella H. S. Williams, 1908, Proc. U. S. Nat. Mus., vol. xxxiv, 



p. 90. 

 Pterinea (Cornellites) flabellum Grabau and Shimer, 1909, N. Am. Index 



Fossils, vol. i, p. 421, fig. 551. 



Description. — Shell large; broad or narrow ovate, oblique, rarely erect; 

 length from two-thirds to nearly equal the height. Left valve more or 

 less convex, often gibbous and arcuate; right valve flat or concave, with 

 a little convexity on the umbo; hinge-line straight, extended on the pos- 

 terior side, and length greater than that of the valve; beak of left valve 

 near the anterior extremity of the hinge-line and curving forward over 

 it ; umbonal region gibbous ; beak of right valve depressed and not rising 

 above the hinge; wing large, triangular, nearly flat, margin concave and 

 extremity acute; ear of left valve a simple rounded convex lobe. Test 

 thick; left valve marked with from six to twelve strong rounded rays, 

 which start near the beak and continue simple to the margin ; the inter- 

 spaces are marked by smaller, alternating costae; there are also strong, 

 concentric, lamellose striae of growth; in the partially exfoliated condi- 

 tion, and in the casts, the ears show the concentric striae and the wings 

 evidences of the rays. 



This species is common in the rather coarse arenaceous Hamilton de- 

 posits of Maryland. The specimens are nearly all exfoliated or impres- 

 sions ; but they show very well the most striking characters of the species ; 



