PLATE X 
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1. A group of specimens of the natural size. 
2and 3. Two fragments, natural size and <9, with some of the zocecial apertures closed. 
4, The basal part of a rather young example, natural size and x9. (See also plate VIII). 
Upper part of the Galena shales, near Cannon Falls, Minn. 
Migs pybOel OPA CHD ICT VAG HOT DATHAM UIC anette tartaric ehieieavictereticiicierleracisinietarsvoiaisteielawieraiierer te 149 
5 to8. Four specimens of the natural size. Fig. 6 presents the unusual condition of raised 
macula. 
9. Surface of fully matured example, x9. 
10. Surface of a young zoarium, X18. (See also plate IX). 
HIgs ll tod) PACH Y DICT YA MD RISH TAT IS iW) livarpertereterterctetste nett reicislspaistetetarsictete eke nlere cketetelctsieheystaleetstetatas 159 
11. Portion of a block of limestone with a group of the slender ramulets of this species, 
natural size. 
12. Surface of an old example, x18, on which many of the zocecial apertures preserve the 
closures. 
13 and 14. Two transverse sections, *25, the first prepared from a young example, the sec- 
ond from one like the original of fig. 12. 
Trenton limestone, Montreal, Can. 
Higsidovbo;20;) ZL RTEONODIOT YA. CONCIGTAMRTexaeiUilitypiaye lature tecarsy ctareleeteintareiercterevaleveleceisieterete eicteretatstatetateretsteeke 160 
15 to 19. Fivespecimens of the natural size, illustrating the zoarial variability of the species. , 
20. Surface of well preserved example x9. (See also plate IX.) 
Upper third of the Trenton shales near Cannon Falls, Minn. 
Rigs :21b0).25) STICLOPORELE A; CRIBROSAUW lt. seereaeer cies cere cits einer er ree tterets 184 
21. Nearly complete zoarium of the prevailing type of this species, natural size. 
22. A thin fragment less regularly developed than usual. 
23. Surface of an excellently preserved example, x9. 
24. Another portion of same X18. In this specimen the mesopores are very oumerous. 
25. Tangential section of an average specimen, X18. In the upper part of the figure the 
section descends to the level of the prostrate portion of the zocecial tubes. (See also 
plate XI.) 
Middle third of the Trenton shales at Minneapolis. 
