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BULLETIN OF THE LABORATORIES 
ridges strongly marked ; we do not however know whether it belongs 
to the first or third types. 
In 1866 Mr. Rudolph Ludwig in Cor. aus Pal. Form, divided 
PleiirodictyiLin into two genera, giving each a new name, thus prac- 
tically abolishing this genus. Pkhychochartocyclus contains those 
forms in which the interior walls of the polyp have longitudinal ridges, 
and these ridges are beset with distinct tubercles. Tacniochartocyclus 
contains those forms in which the ridges are not beset with tubercles 
but are smooth. They correspond to the first and third types of 
Edwards and Haime. 
In Kentucky Fossil Corals, Mr. William J. Davis figures a new 
genus, Pi'octeria. The figures seem to indicate the existence of mural 
pores connecting the. polyps and also of tubercles ornamenting its 
interior. An examination of numerous specimens show that the 
character of the ridges is extremely variable m both tuberculated and 
non-tuberculated forms, and that they are often absent. At any rate 
we do not find in the figure of Procteria any thing to distinguish it 
from Ptchychochartocyclus, and this is only a synonym of Pleiirodictyuni 
even if it be indeed considered necessary to subdivide the genus. It 
will be therefore a matter of interest to learn what the forthcoming 
text may have to offer on that subject. 
Forms have been referred to Pleurodictyum problematicitm from 
various localities in North America and with a range from the Onon- 
daga Group of New York to that of the Waverly Group in Ohio. We 
believe that on study these would be found to belong to several dis- 
tinct species. Notwithstanding this range, the large celled forms of 
corals which pass under the name of Pleurodictyum are usually typical 
of Devonian strata, and are found there most frequently. 
Pleurodictyum has been identified by Rominger and Lindstroem 
with Favosites and Michelinia. The type of the genus is more of the 
character of Michelinia. It seems to us therefore that Pleurodictyum 
has precedence over Michelinia. It contains typically the species of 
Goldfuss, the first type of Edwards and Haime, Ptchychochartocyclus 
stigmosus, Ludwig, and apparently the Procteria of Davis. If it be 
considered admissable to separate the forms without the tubercles, 
Ludwig’s genus Taeniochartocyclus has the precedence. 
We prefer also 10 retain the name Pleurodictyum for the Austra- 
lian form in particular, becaiue the vesiculose tissue of Michelinia has 
not as yet been seen in Australian specimens. For a discussion of the 
