Fig. 15. Bumastus cf. billingsi. A, B, outlines of cranidium and pygidium 
figured on preceding plate, viewed from the side. C, specimen figured by Clarke 
as Bumastus orhicaudatus ; copied from figure 36 on page 722, of Pal. Minnesota, 
III, pt. 2, 1897. 
Fig. 16. Bumastus rowleyi. A, B, outlines of cranidium and pygidium fig- 
ured on preceding plate, viewed from the side. 
Fig. 17. Remopleurides missouriensis. A, outline of specimen figured on 
preceding plate, viewed from the side; B, viewed from the front, showing the 
frontal lobe. 
Fig. 18. Remopleurides striatulus. A, specimen from type locality, in U. S. . 
Nat. Mus., viewed from above; B, lateral view of same; C, short nodose stria- 
tions, magnified 80 diameters. From Trenton limestone at Trenton Falls, New 
York. 
Fig. 19. Ceraurinus scofieldi. Cranidium, from Platteville limestone at 
Minneapolis, Minnesota. Copied from figure 55 on page 735 of Pal. Minnesota, 
III, pt. 2, 1897. 
Fig. 20. Bathyurus spiniger. A cranidium, with fixed cheeks posterior to 
palpebral lobes indistinctly defined. From city quarry, 1 mile southeast of 
New London, near top of Plattin limestone. 
Fig. 21. Pterygometopus intermedins. Cephalic view of enrolled specimen; 
species occurs both in Platteville and Decorah of Minnesota. Copied from 
figure 45 on page 728 of Pal. Minnesota, III, pt. 2, 1897. 
Fig. 22. Pterygometopus confluens. Cranidium from Tyrone member of 
strata exposed at High Bridge, Kentucky. Showing confluence of outer parts 
of first and second pairs of glabellar lobes, as in Pterygometopus eboraceus and 
Pt. lincolnensis. 
Fig. 13. Ceraurus bispinosus. Fragment of cranidium, from Black River 
h’mestcne at Tetreauville, province of Quebec. Copied from figure 4 on plate I 
of Bulletin of Museum of Comparative Zoology, 54, no. 20, 1913. 
Fig. 24. Comarocystites shumardi. A, fragment of theca adjoining anal 
aperture, viewed from interior. B, a single thecal plate viewed from interior. 
From top of quarry in Kimmswick limestone, | mile northwest of West Kimms- 
wick, Missouri. 
PLATE XXIII 
Fig. 1. Mcewanella raymondi. Brachial valve. From Mincke, St. Louis 
County, Missouri; in Kimmswick limestone. 
Fig. 2. Rhynchotrema rowleyi. A, B, pedicel valves, exteriors. C, pedicel 
valve, interior. D, brachial valve, interior. From small knob, 3 miles east of 
Frankford, on road to Louisiana; in Buffalo or Maquoketa shales. 
Fig. 3. Ceraurus plattinensis. A, pygidium. B, hypostoma. From Buford 
Cave, 2 miles west of New London; at top of Plattin limestone. 
Fig. 4. Nileus sp. A, cranidium. B, pygidium. From a coarse lime- 
stone layer immediately beneath the Buffalo or Maquoketa shales, east of the 
home of W. H. Benham, 3 miles south of Frankford, on a branch of Peno creek. 
Fig. 5. Platymerella manniensis. A-D, pedicel valves, interiors. E-H, 
brachial valves. From Lawshe, Adams County, Ohio. In basal part of Brass- 
field formation. 
Fig. 6. Clitambonites cf. diversus. Pedicel valve, lateral view. From 
Mincke, in St. Louis County, Missouri; in Kimmswick limestone. 
Fig. 7. Beatricea gracilis Ulrich. Lateral view of fragment of a much longer 
stem. From quarry east of pike, a short distance north of Auburn, Missouri; 
in Auburn limestone. 
Fig. 8. Zygospira nicolleti. A, brachial valve. B, pedicel valve. From 
Buford Cave, 2 miles west of New Icndon, at top of Plattin limestone. 
