Fig. 16. Bumastus rowleyi. A, cranidium; left side restored; B, pygidium. 
Locality 3 on Sanders branch, in Kimmswick limestone. 
Fig. 17. Remopleurides missouriensis. Cranidium, with the smooth lines 
representing the glabellar furrows darkened. Locality 2 on Sanders branch, in 
Kimmswick limestone. 
Fig. 18. Ceraurus cf. bispinosus. A, B, fragments of cranidia with traces of 
ocular ridge on right side. C, cephalon lacking the free cheeks, genal spine on 
right side restored. Locality 2 on Sanders branch, in Kimmswick limestone. 
Fig. 19. Pterygometopus cf. lincolnensis. Cephalon, left side and part of 
margin restored. From Buford Cave, at top of Plattin limestone. 
Fig. 20. Ceraurus plattinensis. A, an almost entire individual, proximal 
parts of genal spines widened by crushing; from city quarry, one mile southeast 
■of New London. B, Cephalon, from Harvey farm on lower Big Creek, at top of 
Plattin limestone. 
Additional figures of some of the specimens illustrated on this plate appear on 
the following plate. 
PLATE XXII 
Fig. 1. Strophomena incurvata. Curvature of median line of valves of 
specimen figured on preceding plate; with pedicel valve on right. 
Figs. 2, 3. Rafinesquina deltoidea. Outlines of specimens figured on preced- 
ing plate, viewed from the side. 
Fig. 4. Parastrophia hemiplicata var. A, second specimen, from same 
locality as that figured on preceding plate, weathered so as to show spondylium 
formed by dental lamellae, supported by median septum anteriorly. 
Fig. 5. Zygospira deflecta. A, pedicel valve; B, anterior view; from the 
Trenton of Lewis County, New York. Copied from figures 4 a, b, on plate 33, of 
Pal. New York, 1, 1847. 
Fig. 6. Holopea parvula. From Flanagan member, near top of Trenton, 
near Burgin, in central Kentucky. Copied from figure 19, on plate 79, of Pal. 
Minnesota, III, pt. 2, 1897. 
Fig. 7. Holopea concinnula. From the Platteville near Beloit, Wisconsin. 
Copied from figure 6 on plate 79 of Pal. Minnesota, III, pt. 2, 1897. 
Fig. 8. Hormotoma gracilis angustata. From top of Decorah formation at 
Cannon Falls, Minnesota. Copied from figure 32 on plate 70 of Pal. Minnesota 
III, pt. 2, 1897. 
Fig. 9. Conularia sp. A, granular surface, magnified 12 diameters, to show 
arrangement of granules in transverse and in longitudinal rows. B, several 
cross-sections of the enrolled fragments. From same series as the specimen 
represented by figure 9 on the preceding plate. 
Fig. 10. Hyolithes baconi. Cross-section of specimen used for figure 10 B, 
on preceding plate. 
Fig. 11. Hyolithes baconi. Cross-section of specimen used for figure 11 on 
preceding plate. 
Fig. 12. Conularia plattinensis. Imaginary cross-section of specimen simi- 
lar to that used for figure 12 on preceding plate, indicating position of the pair 
of vertical ridges along the median part of the faces, supported interiorly by 
short septal striations. 
Fig. 13. Ctenodonta gibberula. Mould of interior of left valve, from the 
Platteville at Minneapolis, Minnesota. Copied from figure 37 on plate 42 of 
Pal. of Minnesota, III, pt. 2, 1897. 
Fig. 14. Modiolopsis consimilis. Right valve, from the Stones river group 
at Murfreesboro, Tennessee. Copied from figure 17 on plate 42 of Pal. Minne- 
sota, III, pt. 2, 1897. 
