

312 S. WELLER FAUNA OF THE FERN GLEN FORMATION 



ATHYRIS LAMELLOSA (L'Ereille) 

 Plate 14, figures 5-6 



1835. Spirif er lamellosus L'Eveille, Meiuoires de la Societe Geologique de 



France, volume 2, page 39, figures 21-23. 

 1858. Athyris lameilosa Davidson, British Fossil Brachiopoda, volume 2, page 



79, plate 16, figure 1 ; plate 17, figure 6. 

 1875. Athyris lameilosa ? Meek, Paleontology of Ohio, volume 2, page 283, plate 



14, figures 6a-6. 

 1887. Athyris lameilosa De Koninck, Faune du Calcaire Carbonifere de la Bel- 



gique, part 6, page 79, plate 21, figures 1-5. 

 1895. Athyris lameilosa H. & C, Paleontology of New York, volume 8, part 2, 



plate 46, figures 16-20. 



Description. — Shell transversely subelliptical, the valves moderately 

 and subequally convex, the hinge line short. Pedicle valve obscurely flat- 

 tened along the median line in the posterior half of the shell, the flatten- 

 ing gradually changing into a slight, ill defined mesial sinus anteriorly, 

 the anterior margin of this portion of the shell sometimes being bent 

 toward the opposite valve and produced into a mesial lingual extension 

 of moderate size ; beak small, pointed, incurved, and in close contact with 

 the umbo of the brachial valve. Brachial valve slightly flattened along 

 the mesial line posteriorly, the flattening being gradually transformed 

 into an obscure, flattened mesial fold anteriorly, which sometimes be- 

 comes rather prominent near the anterior margin. Surface of both 

 valves marked by parallel, concentric, lamelliform expansions which are 

 commonly in large part destroyed, only their bases being retained. 



The dimensions of an average specimen from the Fern Glen fauna, 

 exclusive of the lamelliform expansions, are: Length, 22 millimeters; 

 width, 26.5 millimeters; thickness, 11 millimeters; on the same example 

 the anteriormost lamelliform expansion is produced 11 millimeters and 

 is still not complete. 



Remarks. — Individuals of this species in the Fern Glen fauna do not 

 usually grow to so great a size as do specimens of the same species in the 

 superjacent Burlington limestone, but in all essential characters the 

 shells seem to be identical with each other and also with European mem- 

 bers of the species. The largest Fern Glen specimen observed, a some- 

 what crushed individual, has a width of 44 millimeters, which is fully as 

 large as some of those in the Burlington limestone. 



