PLATE LXIX. 
vFigui-es 1-10,13 by G. B. Simpson; 11,12 by K. B. Whitfield.) 
’ Genus PENTAMERUS, Sowerby. 
Page 236. 
Pentamerus oblongus, Sowerby. 
Pig. 1. Dorsal view of an internal cast of a small shell, broadly trilobed and having a similar outline to 
young forms of the variety suh7-ecUis (see figs. 2, 8) though with much shallower valves. 
Niagara dolomites. Richmond, Indiana. 
Pentamerus oblongus, vur. subrectus, viir. nov. 
See Plate 68. 
Figs. 2, 3. Dorsal and ventral views of a small specimen of subquadrate outline, trilobed exterior, and 
showing the single median septum in both valves. 
Figs. 8-10. Dorsal, profile and ventral views of a normal mature individual; showing the characteristic 
subquadi'ate outline, jirominent umbo of the iiedicle-valve, trilobate exterior, and linear median 
depression on both valves. 
Niagara beds. Castle G-rove towfiship, Jones county, loioa. 
Pentamerus oblongus, Sowerby. 
4, 5. Dorsal and ventral views of a small elongate internal cast in chert, similar in contour and size 
to a form occurring at Utica, Indiana, in association with the variety cylindricus. This shell 
occurs in the clieid of the Maquoketa region near Dubuque, Iowa, but not in immediate asso¬ 
ciation with the var. subrectus. 
Niagai-a beds. Jones county, Iowa, 
6. Dorsal view of the umbonal region of an internal cast in chert; showing the cavities left by the 
septum and septal plates, the deltidium and the lateral divisions of the hinge-plate. X 2. 
Niagara beds. Monmouth, loioa. 
7. Ventral view of a subquadrate shell with the lobation of the surface distinctly defined. The dor¬ 
sal view of this specimen is given upon plate Ixviii, fig. 1. 
Clinton group. Rochester, New York. 
Pentamerus oblongus, var. cylindricus. Hall and Whittield. 
Figs. 11, 12. Profile and dorsal views of the original specimen of this variety ; showing the elongate form 
and a faint trilobation of the exterior. 
Niagara group. Near Louisville, Kentucky. 
Pentamerus oblongus, Sowerby. 
Fig. 13. Dorsal view of an internal cast of a large and evenly convex shell having the ovoid foi’m and 
i-egular contour of the var. Maquoketa (see plate Ixvii, figs. 11-13), which, however, is a per¬ 
sistently smaller form. 
Niagara dolomites. Locality uncei'tain; probably No^'tlien'ii Indiana. 
Fig. 14. An outline sketch of a large brachial valve having the broadly ovate form and trilobed exterior 
of the specimens from Yellow Spring's, Ohio, represented on plate Ixviii, figs. 3-5. 
Niagara dolomites. Probably from the vieinity of Riclmnond, Indiana. 
Figs. 
Fig. 
Fig. 
