20 A COXTRIBUTIOX TO THE LoWER DevOXIAX FaUXAS OF MakYLAXD 

 ACTIX'OPTERIA TEXTILIS YAK. AREXARIA (Hall) 



Plate LXXVII 



Avicula textilis var. arenaria Hall, 1859, Nat. Hist. N. Y., Pal., vol. lii, p. 465, 



pi. cix, figs. 1, 2; pi. ex, fig. 2, 1861. 

 Avicula textilis var. arenaria Weller, 1903, Pal. N. J., vol. iii, p. 3G0, pi. 1, 



fig. 1. 



Description. — "Shell large, obliquely subovate; the proportions oi' 

 length and height variable. Left valve becoming moderately and regularly 

 convex from the base, the greatest convexity being about the first third 

 below the hinge-line. Posterior wing large, extending along the margin 

 of the body of the shell halfway from beak to base. Anterior wing small, 

 triangular, wrinkled. The right valve is slightly concave, smaller than the 

 other, faintly marked by the radiating ribs, which sometimes are scarcely 

 seen. Surface marked by strong radiating ribs sometimes regularly 

 dichotomizing and subequal, and in other specimens quite unequal, show- 

 ing a few stronger ribs, with several finer ones betAveen, and these are 

 crossed by strongly elevated imbricating lamella." Hall, 1859. 



Several specimens from the Oriskany of the state are referred to this 

 variety. The close resemblance between A. communis, the typical .-i. 

 textilis and the varietal form, casts doul^t upon the identification of the 

 forms as they occur in Maryland. 



Occurrence. — Oriskany Formatiox, Eidgely Member. Warren 

 Point, Pennsylvania; west side of Queen's Point opposite Keyser, Miller's 

 Spring, West Virginia. 



Collections. — Maryland Geological Surve}^, U. S. National Museum. 



ACTIXOPTERIA VIRGIXICA 11. Sp. 



Plate LXXVIII, Figs. 1, 2 



Description. — Body of the shell obliquely ovate, gibbous, maximum in- 

 flation about one-third the distance from the beak to the base. From this 

 point the shell arches rapidly to the beak and gently to base ; contracts 

 rapidly on either side of the umbo near the beak and less so as the distance 

 from beak increases; beaks not prominent; posterior wing not sharply 



