PLATE XXTI. 
Lichenalia concentrica Hall. (Page 61.) 
[See also PI. XXVI, figs. 7-10.] 
Fig. 1. A tangential section, X 6, passing close to the surface of the zoarium and cutting 
one of the meandering canals. 
2. Portion of a tangential section, X 20, cutting the high anterior end of the peri- 
stome and a few of the connecting walls. 
3. A tangential section, X 20, passing through a lower portion of the zoarium than 
in fig. 2. The lower portion of the figure illustrates the zooecia and mesopore- 
like structures of the mature region, the middle portion, the oblong or rectan- 
gular shape of the zooecia in the immature zone, while in the upper part of the 
drawing arc shown portions of the concentric rings of the epitheea. 
1. A portion of a tangential section,. X 20, illustrating the nature of the walls of 
the mesopore spaces. 
f). A vertical section, X 20, illustrating the following characters: z, the zooecia; c, one 
of the canals, covered above: u h, undulating base of zoarium; w, walls forming 
the mesopore-like spaces; p, the extremely high posterior portion of the peri- 
stome; a, the low anterior portion of the peristome' and p', a posterior portion 
of the peristome cut obliquely. 
0. A more diagrammatic vertical section, X 20, showing especially the low and high 
portions of the peristome and the walls of the interzocEcial spaces. 
Rochester shale, Lockport, N. Y. 
Stictotrypa punclipora (Hall). (Page 61.) 
[See also PI. XXIV, figs. 2fi, 27.) 
7. A nearly complete zoarium, natural size, illustrating the usual method of growth. 
8. A portion of the surface of the same, X 20, showing the characteristic notch 
or cleft in the anterior part of the peristome. 
Rochester shale, Grimsby, Ontario. 
'.). A portion of a tangential section, X 20, passing through both mature and imma- 
ture regions and illustrating especially the rhomboidal shape of the immature 
zooecia. 
10. A tangential section through the mature region, X 20. 
11. A vertical section, X 20. 
Rochester shale, Lockport, N. Y. 
Rhinopora curvata Ringueberg. (Page 60.) 
12. A vertical section, X 20, illustrating the bifoliate growth and other characters. 
13. Surface of a typical example, X 8. 
Rochester shale, Grimsby, Ontario. 
110 
