PLATE XXXII. 
(Figures 1-3, 7-10,12-15 by R. P. Whitfield; 4-6,11 by F. B. Meek.) 
Legend: A. Delthyi ium. a. Anterior adductors. 
t. Teeth. a'. Posterior adductors. 
8. Dellhyrial callosity. r. Diductors. 
Genus SPIRIFEE, Sowerby. 
Page 1. 
Spirieer lateralis, Hall. 
Fig. 1. Dorsal view of a large and rather convex individual. 
Fig. 2. Front or marginal view of the same specimen. 
Fig. 3. An enlargement of the surface ; showing the pustulose stria on the plications. 
Warsaw limestone. Warsaw, Illinois. 
Spirieer tenuimarginatus, Hall. 
Figs. 4, 6. Views of an individual of normal size. 
Keokuk group. Keokuk, Iowa. 
Spirieer rostellatus, Hall. 
Fig. 5. A dorsal view of the original specimen. 
Keokuk group. Skunk River, Iowa. 
Spirieer Logani, Hall. 
A dorsal view of the original specimen ; showing the great size and general external characters 
of the species. 
The interior of a portion of the pedicle-valve ; showing the articulating apparatus and the adduc¬ 
tor and diductor musculars scars. 
Keokuk limestone. Near Nauvoo, Illinois. 
Spirieer cameratus, Morton. 
Fig. 9. A large individual; showing the usual angular fasciculation of the plications. 
Fig. 10. Front view of the same specimen ; showing the relative size of fold and sinus. 
Coal Measures. Missouri. 
Fig. 11. An individual with broad, low fascicles composed of rounded plications. The breadth of the 
fascicles is somewhat unusual. 
* Coal Measures. Iowa. 
Fig. 12. An example with the fascicles reduced to sharp, coarse, angulai-, bifurcating plications. This form 
and that represented in fig. 11, indicate the extremes of variation in exterior in this species. 
Fig. 13. An enlargement of a portion of the internal cast of the brachial valve ; showing the narrow mus¬ 
cular impression and the anterior and posterior adductor scars. 
Fig. 14. An enlargement of a similar portion of a cast of the pedicle-valve ; showing the composition of the 
muscular area. 
Fig. 15. An enlargement of the surface ornamentation. The surface is marked by extremely fine concentric 
strise, which are minutely papillose. Distinct imbricating lines of growth supervene towards 
the anterior margin. 
Coal Measures. Ohio and Illinois. 
Fig. 7. 
Fig. 8. 
