American Paleozoic Bryozoa., 269 
easy task. I therefore propose the name of prominens for fig. 3. It is 
distinguished by its large und remarkably prominent monticules, 
which, so far as observed, never coalesce. Their diameter will average 
about .15 of an inch; their height about .05 inch; in the space of one 
half inch square, about sixteen may be counted. The branches are 
usually sub-cylindrical, with an average diameter of about .4 ofan inch. 
This variety is apparently restricted to a few feet of strata, and 
marks an horizon about 200 feet above low water mark. 
The variety represented by fig. 4, was eataluzued by me in 1880, 
under the name of plana. It has an extended geographica! as well as 
geological range, and is, perhaps, the earliest representative of the 
genus Constellaria, occurring first in the Trenton group of Canada. 
Next it appearsin Tennessee and Kentucky, in Safford’s “ Orthis Bed.” 
This bed I regard as the upper member of the Trenton group. In the 
Cincinnati group it is rare near low water mark in the Ohio river. It 
next appears at a height of nearly 300 feet above that mark, where it 
again has a range of only a few feet. It is mainly distinguished from 
typical C. florida, by its nearly smooth surface. The Trenton , 
Specimens are larger than those from Cincinnati, and their branches 
frequently anastomose, a feature not observed in specimens from this 
locality. 
CoNSTELLARIA LimrraRis, Ulrich (PI. XIV., figs. 5, 5a). 
(Stellipora limitaris, Ulrich, Jour. Cin. Soc. Nat. Hist., Vol. IL., p. 126, Pl. XII., figs. 8-8c. ) 
My origina] description and figures (loc. cit.) of the minute structure 
of this species being not as good as they might he, I have refigured the 
sections, and written the following more complete, and, I believe, 
reliable diagnosis of the internal characters, as they are shown in 
carefully prepared thin sections. 
Tangential sections (Pl. XIV., fig. 5) show that the true zoccia are 
bunched together between the somewhat irregular rays of the “mac- 
ule,” and that they are here separated from each other by rather thick, 
‘solid interspaces, which usually inclose a variable number of minute 
cells, that may be of the nature of spiniform tubuli. The “ macule”’ 
are composed of a large number of smaller, thin-walled, polygonal 
interstitial cells, that only rarely attain half the size of the true cells. 
In the spaces between the stellar “macule,”’. the true zoecia are cir- 
cular, with moderately thin walls, and an average diameter of ;1>th of 
an inch, They are usually completely isolated by a single row of 
small, angular interstitial cells. 
