PLATE XXXVI—ContinuetL 
Genus SP I RIF ERIN A, d'Orbigny. 
Page 51. 
Spirifekina Kentuckiensis, Slummrd. 
Fig. 14. The exterioi- of a pedicle-valve. 
Fig. 15. An oblique view of the interior of the pedicle-valve; showing the median septum and muscular 
impressions. 
Fig. 16. The cardinal view of an exfoliated shell; showing the character of the area and deltidial plates. 
Coal Measures. Illinois. 
Genus SPIRIFER, Soaverby. 
Page 1. 
Spirifer fimbriatus, Connid. 
See Plate 38. 
Fig. 17. The internal cast of a pedicle-valve ; showing the composition of the muscular area. 
Schoharie grit. Schoharie, N. Y. 
Figs. 18, 19. Dorsal and profile view’s of a normal examjile; showing the lateral plications and the con- 
centi'ically striated surface covered with the bases of spinules. 
Upper Heldei’berg group. Western JXeiu York. 
Fig. 20. An enlargement of the surface ; showing the bases of the spinules. 
Fig. 21. A pedicle-valve which I'etains a portion of the spinules. 
Hamilton group. Western New York. 
Fig. 22. A cardinal view of an internal cast of conjoined valves; showing the vascular sinuses. 
Hamilton group. Hardy county, Virginia. 
Spirifer PRAiMATURUs, Hall. 
Fig. 23. The internal cast of a pedicle-valve, retaining a trace of a median septum. 
Chemung group. Allegany county, N. Y. 
Fig. 24. The internal cast of a pedicle-valve; showing the impressions of the dental lamellae and a low 
median septum. 
Fig. [25. Another cast of the pedicle-valve, which retains the muscular impression. 
Chemung group. Meadville, Pennsylvania. 
Spirifer settgerus, Hall. 
Figs. 26, 27. Dorsal and profile views of a rotund, normal example; showing the incipient deltidial plates 
and fimbriated lamellae. 
Chester limestone. Chester, Illinois. 
Spirifer pseudolineatus, Hall. 
Fig. 28. The cardinal view of a large example. 
Fig. 29. A dorsal view of the same sjiecimen ; the shell has been exfoliated on different parts of the sur¬ 
face, presenting the features shown in figure 30. 
Fig. 30. An enlargement of the surface ; showing the tubular character of the surface spinules, and, at 
e, the penetration of these tubes beneath the epidermal layer of the shell. The spinules are 
reju’esented as simple, short and blunt, but they are, on the contrary, furnished with lows of 
lateral bl anches, and are long, slender and acute. 
Keokuk limestone. Keokuk, Iowa. 
