PLATE XIV. 



PAGE. 

 Tigs. 1 to 8. PHYLLODICTYA VAKIA, n. sp 144 



1. A fragment with subparallel margins, natural size. 



2. Surface of same xg. 



3. Two rows of apertures xjg; shows the papillose character of the ridges. 



4. 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 xis. The internal characters are but illy preserved in even the best 



of the specimens sectioned. 



6 and 7. Old zoarium of the natural size with a portion of its surface xg. With age the 

 maculse become more distinct and the longitudinal arrangement of the zooecial 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 to 11. EURYDICTYA MULTIPORA (?Hall, 8p.) 139 



9. Fragment of a slightly undulating expansion, natural size. 



10. Surface of same, xg. 



11. Small portion of same, xis. 



Upper third of the Trenton shales, St. Paul. Survey Museum, Reg. No. 5942. 

 Figs. 12 to 21. ARTHROPORA SIMPLEX Ulr 177 



12. Two segments of the usual size. 



13 and 14. Two biflurcating segments, probably abnormal; natural size. 



15. Several segments preserved in their natural positions, natural size. 



16. Surface of a well preserved fragment, xig. 



17. Several zooscial apertures of same, X35. Jn many specimens the longitudinal prolon- 



gations from the ends of the inner ring of papillaa are longer, in some cases even 

 joining. 



18. Irregularly divided basal joint, natural size. 



19. The lower part of same, X9. It is difficult to make out ths apertures, the whole sur- 



face appearing to be covered with closely intertwining strias. 



20. Vertical section, xis. 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. In the middle third the section sinks to the level of 

 the prostrate part of the zorecia 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 have only the prostrate part of the zocecia and the dense margin. 

 Middle third of the Trenton shales at Minneapolis. 



Figs. 22 to 25. ARTHROPOHA BIFURCATA, n. sp 178 



22. A small segment natural size and its upper part xi8. 



23 and 24. Two old segments, the last one probably the basal, of the natural size. 



25. Surface of the original of flg. 23, xis, illustrating the aged condition in contrast with 



the youthful stage represented in flg. 22. 

 Upper third of the Trenton shales, St. Paul. 



Fig. 26. ARTHROPORA REVERSA, n. sp . 178 



Natural size view of an average segment, and a portion of its surface x35. 

 Base of the Galena shales at St. Paul. 



