Figs. 
Figs. 
Figs. 
Figs. 
Figs. 
Figs. 
Figs. 
PLATE VIII. 
PAGE. 
1to3. RHINIDICTYA MUTABILIS Ulr................ etlarel otlata eters eto ite loch Yatal lel ote iatetetetat Tele evecare 125 
Three portions of an old example of this species *9, showing, in 1, the thick, rounded 
and granulose margin, in 2, the shape of the zocecial apertures at the upper extremity 
of the specimen, and in 3, chein form near the lower end of same. (See also plates 
Vi and VIL.) 
Aandip. 1 LACHYDICDY A UML ACE IT wales psepersietaictale sate he eete ete rtate let tateretnteretetete fe otatelelajereiiet sjevetalaieratatetays 157 
Two fragments of the natural size, and one of them representing the basal part of the 
zoarium, <9. (See also plate X, and remarks on p. 158.) “ 
GubO 210! sa RENT DLO MYA: Sel CHUAN ln apace ape otey ape tenet ebatisi atone taney eters ecu ere peceratedetalefe tau fielerehirelsiaaetate/sictalalaletotetayare 131 
6and7. The basal part of a specimen of the natural size and <9, One of the branches has 
three, the rest of the zoarium four rows of zocecia. 
8. A delicate fragment with only three rows of zocecia, 
9and10. A branching fragment of the natural size and the lower half x9, This has from 
five to seven rows of apertures. 
Lower third of the Trenton shales at Minneapolis. 
11 to17. PACHYDICTYA ACUTA (Hall) and varieties..... Mn roa boo spond OT aoS oop od aonen ose 155 
Figs. 11 and 12. A specimen of the natural size anda portion x9. Trenton limestone, 
Trenton Falls, N. Y. 
13. A very small specimen, with only six and seven rows of zocecia, from the Galena lime- 
stone near Fountain, Minn. x 
14 to 16. Three specimens from the Galena shales near Cannon Falls, Minn. 
17. Surface, X9, of a well preserved fragment from the same horizon and locality as the pre- 
ceding. (See also plate IX.) 
L8yarid) 193 y EAC Hava CUSYZA HUES EH GHAGNIS youl) SS Poe eteseyn ser otenslote iatereyereteseleYate etateiotel elesesetelstobetefelol=tetenmierarstelefetererstetals 154 
18. A very nearly perfect zoarium of this species, natural size, from the lower part of the 
Galena shales at St. Paul. Later collections show that this species is exceedingly 
abundant at that locality and that the specimen here figured divides with greater 
frequency than usual. 
19. Enlargement of the beautifully ornamented surface of same, X18. (See also plate IX.) 
MDa W0) PA tapas YC BTA DIC NOCHE U/AIDI) Bl aaduandadans ooodedcodassanonoooowonbd sncdoedosune 151 
20 to 24. Five specimens of the natural size, illustrating the variable character of the zoaria. 
25. Surface of fig. 24, <9. 
26 and 27. A frond of the natural size and a portion of its surface <9, traversed by irregular 
grooves caused by interruptions in the development of the zocecia. (See also plate IX.) 
Upper third of the Trenton shales at St. Paul. 
28 HO.S4y. PACH y-DICI YAS TINUE Re VAUIVA Guam Ol Te steteseteteraratsiefe\'siniaistelelelaiaistelefatesatoisteas ORE Rh a on 152 
28 to 30. Three specimens of the natural size, the last one the widest seen. 
31 and 32. A very narrow and seemingly young example, natural size and the upper part *9. 
33 and 34. An excellently preserved fragment of the natural size and a portion x9. This pre- 
sents the fully matured condition of the species. (See also plate IX.) 
Middle third of the Trenton shales at Minneapolis and St. Paul. 
