298 Thirty-fifth Report on the State Museum. 



hinge- line 15 mm. The smallest specimen measures 10 mm. in 

 length of body and hinge-line, and 6 mm. in height. 



In form and surface characters this species is quite unlike any other 

 described from these rocks. In some respects it resembles A.exwna, 

 but has more extended wing and less elongate body. 



Formation and locality. In the Marcellus shale at Littleville near 

 West Avon, Livingston county, N. Y. 



ACTINOPTERIA DORIS. 



Actinopteria Leander, Hall. Pal. N. Y., vol. v, pt. 1. Plates and Explana- 

 tions. PI. 17. fig. 4. Jan., 1883. 

 Actinopteria Doris, Hall. Pal. N. Y., vol. v, pt. 1. UnpuUislied . 



Shell small, sub-rhomboidal; body obliquely sub-ovate; length a 

 little greater than the height ; margins regularly rounded, sloping 

 abruptly from the upper part of the posterior side to the beak. 

 Left valve depressed-convex. Right valve unknown. Hinge-line 

 straight, about equal to the length of the shell (imperfect in the 

 specimen described). Beak depressed, inclined forward, situated at 

 the anterior third of the hinge. Umbonal region not defined, sub- 

 tending an acute angle. Ear not observed. Wing large, flat, not 

 distinctly defined ; margin concave ; extremity acute. 



Test thin ? marked by regular, equal, rounded radii, with wider 

 flat interspaces, and sometimes with obscure intermediate rays. 

 The wing shows finer rays, somewhat crowded at its junction with 

 the body. The fine, concentric lines of growth are stronger on the 

 anterior of the valve, giving a cancellate aspect to the surface. 

 Ligamental area with one or two longitudinal grooves. 



The specimen has a length of 18 mm., height 16 mm. 



Formation and locality. In the Marcellus shale at East Bloomfield, 

 Ontario county, N. Y. 



Actinopteria subdecussata. 



Pteronites subdecussata, Hall. MS., vol v. 1877. 



" " " S. A. Miller. Cat. Anier. Pal. Foss., p. 202. 



1877. 



Actinopteria subdecussata, Hall. Pal. N. Y., vol. v, pt. 1. Plates and Ex- 

 planations ; PI. 17, figs. 23, 25-27, 29-31 ; pi. 19, fig. 25. Jan., 1883. 



Shell large, sub-rhomboidal, very oblique ; body elongate sub-ovate ; 

 height about one-third less than the length ; margins regularly 

 curved, becoming more extended on the posterior side. The left 



