PLATE ‘XLV. 
(Figures 1-3, 6-12, 16,18-24, 26-28, by K. P. Whitfield;^ 4,15, 13-15, 25, 29, 30 by IS. Emmons; 17 by G. B. Simpson.) 
Genus ATHYRIS, McCoy. 
Page 83. 
Athyris vittata, Hall. 
Figs. 1-3. Dorsal, profile and anterior marginal views of a normal individual; showing its comparatively 
short transverse diameter and the development of the median fold and sinus. 
Fig. 4. The hinge-plate as viewed from above ; showing the trilobation of the antei'ior margin, the deep 
depression of the median portion, the coalescence of the lateral portions with the socket-walls, 
and the large, unobstructed visceral foramen. The lateral lobes are the bases of the crura and 
are incorrectly represented as entire at their outer extremities. X 3. (c.) 
Fig. 5. The interior of the cardinal portion of conjoined valves, the brachial valve being above. This 
view shows the elevation of the anterior face of the hinge-plate, the internal opening of the 
visceral foramen, the extension of the median lobe of the plate, the thickened crural plates, 
the crura attached to the crural lobes and their mode of union with the primary lamellse of 
which a portion is shown. X 3. (c.) 
Hamilton group. Falls of the Ohio. 
Athyris Cora, Hall. 
Figs. 6-10. Dorsal, profile, cardinal, ventral and frontal views of the original specimen, which is somewhat 
exfoliated about the umbones; showing the sublenticular contour and the low median sinus on 
each valve. 
Hamilton group. Delphi, JSf. Y. 
Athyris spiriferoides, Eaton. 
Fig. II. Dorsal view of a large and senile individual, having the surface lamellse highly developed and the 
median fold conspicuously elevated at the anterior margin. 
Fig. 12. The interior of a pedicle-valve; showing the mature condition of the foramen without deltidial 
plates, the pedicle-, adductor and diductor scars. 
Hamilton group. /Soft shales of Western New York. 
Fig. 13. A preparation of the brachidium, one of the spiral cones being removed to expose, the structure 
of the loop. This figure shows the depressed ventral surface of the cones, the mode of attach¬ 
ment of the crura to the primary lamellse, the anterior position of the loop, its broad lateral 
branches and saddle, the long stem, and the width and extent of the accessory lamellse. 
X 2. (c.) 
Hamilton group. Alpena, Michigan. 
Fig. 14. An enlargement of the hinge-plate ; showing its subquadrate-triangular outline, the oblique aper¬ 
ture of the visceral foramen, the thickening of the crural bases and the elevation of their 
posterior extension in the form of socket-walls ; also the dental sockets and the slight submar¬ 
ginal thickening outside of them. X 3. 
Fig. 15. An anterior view of the same specimen ; showing the stout crural plates resting upon the bottom 
of the valve, and foi’ming the inner wall and base of the dental sockets. In the background 
are seen the posterior elevation of the socket-walls, the visceral foramen and the beak. X 3. 
Hamilton group. Clarke county, Indiana. 
Fig. 16. A dorsal view of conjoined valves of a small individual on which the surface lamellae are few 
and distant. 
Hamilton group. Westeni New York. 
Fig. 17. The interior of a brachial valve; showing the structure of the articulating apparatus and the 
elongate scar of the adductor muscles. 
Hamilton group. Falls of the Ohio. 
