84 VINE: CARBONIFEROUS AND PERMIAN POLYZOA. 
Cystodictya, yet in the minute structures of the two, similar charac- 
teristic features prevail, such as vesiculse between the cells and on 
the margins. In comparing these structures, however, with true 
Coelenterate tissues I do not think that a similarity between them 
can be sustained ; yet at the same time I shall be happy to learn what 
the future opinions of others may be who take an opposite view. 
Explanation of Plates. 
Plate III. 
Fig. 1. Fragment of ^Mm/Z^/rt, from Castleton, Derbyshire. 
Fig. 2. The same enlarged, showing superficial arrangements of Zooe- 
cla in the branch, irregularly placed. 
Fig. 3. Semi-transparent longitudinal section of Yorkshire example, 
showing peculiar zig-zag character of axis. 
Fig. 4. Opaque section in which the edges of the Zooecia are attached 
to the bar, right-hand side of branch. 
Fig. 5. Transparent section enlarged about 60 dia. In this specimen 
the interspaces between the two cells are vesiculate, and 
the bars are seen to be triplicate. Inner part of the cells 
filled with calcareous matter. 
Fig. 6. Two marginal Zooecia, (right hand), in which the granulate 
character of the bars and cells are shown. Opaque, en- 
larged about 40 times. 
Fig. 7. A single cell showing pear-like character of the aperture with 
vesiculate interspaces. Transparent mag. about 40 times. 
Fig. 8. Opaque ; outline of aperture of top cell in fig. 5 before it was 
sectioned. 
Fig. 9. Transparent section showing the dense edge and the vesicula 
of the inner portion of the margin up to the first bar. 
Magnified about 50 times. 
Fig. 10. Section (Hairmyres, Scotland), showing the position and 
general character of the Gonocyst, in relation to the other 
portion of the branch. 
Fig. 11. Gonocyst and vesiculate margin, with oblong outlines of the 
bases of the three cells within the first bar of fig. 10. 
Magnified about 60 times. Drawn with camera lucida. 
Fig. 12. Yorkshire example, transverse section, showing the general 
