PLATE XIV. 
Figs. 1 to 8. PHYLLODICTYA VARIA, D.SDP..-. sees cece ee nec e cere tenn e tees eee teen eee e ee eeeceencees 
1. A fragment with subparallel margins, natural size. 
Surface of same 9. 
Two rows of apertures *18; shows the papillose character of the ridges. 
Vertical section, 18. By an oversight the diaphragms are wanting in this figure. 
Each tube should have one crossing it at right angles at a point about midway between 
its aperture and the mesial line. — 
5. Tangential section X18. The internal characters are but illy preserved in even the best 
of the specimens sectioned. 
6and7. Old zoarium of the natural size with a portion of its surface x9. With age the 
maculz become more distinct and the longitudinal arrangement of the zocecial aper- 
tures less obvious. : 
8. Portion of a zoarium larger and wider than usual; natural size. 
Middle third of the Trenton shales at Minneapolis. 
Figs. 9 to11. EURYDICTYA MULTIPORA (?PHall, SP.)........-22 ssc ceee ee cose cere ee eee t eee seen teenies 
9. Fragment of a slightly undulating expansion, natural size. 
10. Surface of same, <9. 
11. Small portion of same, X18. : 
Upper third of the Trenton shales, St. Paul. Survey Museum, Reg. No. 5942. 
Figs. 12 to 21. ARTHROPORA SIMPLEX UIPr.......... cee ec ee eee cet e cee cree cece reece ce tence tence 
12. Two segments of the usual size. 
13 and 14. Two bifiurcating segments, probably abnormal; natural size. 
15. Several segments preservel in their natural positions, natural size. 
16. Surface of a well preserved fragment, X18. . 
17. Several zocecial apertures of same, X35. In many specimens the longitudinal prolon- 
gations from the ends of the inner ring of papille are longer, in some cases even 
joining. 
18. Irregularly divided basal joint, natural size. 
19. The lower part of same, <9. It is difficult to make out the apertures, the whole sur- 
face appearing to be covered with closely intertwining striz. 
20. Vertical section, *18. showing the form of the zocecia, the hemisepta, and other fea- 
tures. : 
21. Three portions of a tangential section, x35. In a the right hand third shows the struc- 
ture just beneath the surface. Inthe middle third the section sinks to the level of 
the prostrate part of the zocecia and in some of them both kinds of hemisepta are 
shown. On the left side the dark band represents the noncelluliferous margin. In 
c we haye only the prostrate part of the zocecia and the dense margin. 
Middle third of the Trenton shales at Minneapolis. 
Figs. 22 to 25. ARTHROPORA BIFURCATA, -I. SP..e.e.eee cece eee e eee e tee e eset eee eee er nte cn see aces 
22. A small segment natural size and its upper part *18. 
23 and 24. Two old segments, the last one probably the basal, of the natural size. 
25. Surface of the original of fig. 23, x18, illustrating the aged condition in contrast with 
the youthful stage represented in fig. 22. 
Upper third of the Trenton shales, St. Paul. 
Fig. 26. ARTHROPORA REVERSA, UO. SD..esseeecec se see eens cere ete eetecee ce ceee ences eteesecenees : 
Natural size view of an average segment, and a portion of its surface x35. 
Base of the Galena shales at St. Paul. 
Pet 
139 
177 
178 
178 
