42 BKYOZOAN FAUNA OF THE ROCHESTER SHALE. 
a similar method of growth, but the few mesopores and polygonal zocecia distinguish it 
without considering the different internal characters. The representative of C. elegantula 
in Europe seems to be the form described by Nicholson in 1884 from the Buildwas beds 
of the Wenlock as Callopora nana.a Indeed, the two species are so closely related that the 
writer can not point out any satisfactory means of distinguishing them. Internally the 
two are alike and externally the only difference noted is that the average diameter of the 
zoarial branches of C. elegantula is about twice that of the European species. This, how- 
ever, is a minor character and further investigation will probably show that C. nana can 
scarcely be regarded as more than a variety of O. elegantula. 
Occurrence. — Very abundant in the Rochester shale at Rochester, Lockport, Niagara 
Falls, and other localities in New York, and al Grimsby, Hamilton, and Thorold, Ontario. 
Also abundant in the Osgood beds of the Niagaran at Osgood and Waldron, Ind. The 
species is also found in Niagaran strata at numerous points in the Mississippi Valley. 
Catalogue numbers, 35534, 35533, 44129, 3552S, U. S. National Museum. 
Callopora clausa n. sp. 
Pi. XV, Qgs.9 li'. 
This neat little species agrees with 0. elegantula in growth and general characteristics, 
but differs in the following respects: Mesopores arc almost entirely wanting at the surface, 
the few that are present being usually restricted to the maculae. As a result, the zocecia 
arc polygonal in outline and contiguous. Internally C. clausa may be distinguished from 
C. elegantula by the more abundant diaphragms in the zooecial tubes, these being about 
twice as numerous in both the axial and peripheral regions. Vertical sections show that 
mesopores develop, as usual, with the inception of the peripheral region, but close before 
the surface is reached. The zooecial walls are greatly thickened in the peripheral region 
by a dense deposit of tissue and in tangential sections the walls are seen to vary in thick- 
ness from one-half to two-thirds the diameter of the zooecial tubes, although at the surface 
the walls appear quite thin, because here only their crest or summit is seen. 
C. clausa is probably more closely related to ('. magnopora I han to the genotype, but the 
size of the zoariuin and the tabulation of the ZOOecia are so different that the two will 
hardly be confused. The zoariuin of small, cylindrical, smooth branches, 3 to 1 nun. in 
diameter, the large, angular zooecia, 4 to 5 in 2 mm., Jew mesopores, and internally the 
numerous diaphragms in both zooecia and mesopores arc the specific characters of this 
interesting form. 
Occurrence. — Rather uncommon in the Rochester shale at Lockport and Rochester, N. Y., 
and Grimsby, Ontario. Several specimens were also obtained in. the Osgood beds at 
Osgood, Ind. 
Catalogue numbers, 44130, 35531, 35530, U. S. National Museum. 
Callopora magnopora Foerste. 
PI. XV, figs. 1-8; PI. XXVI, flg.3. 
Callopora magnopora Foerste, Bull. Sci. Lab. Denison Univ., 11, 1<S*7, p. 173; III, pi. 1(1, fig. 5. 
Callopora magnopora Foerste, Geol. Survey Ohio, VII, 1895, p. 600, pi. 29, fig.. 5. 
This species, which is not uncommon in the Clinton of Ohio, seems to be absent in the 
corresponding strata of New York, where, however, it reappears in the succeeding Rochester 
shale. Foerste's figures and description are inadequate, and the following description is 
based upon specimens received from that author. 
Zoarium more or less irregularly ramose, the branches sometimes being subcylindrical 
and regularly dividing but often consisting of gnarled stems irregular in shape: diameter 
of branches varying from 5 to 12 mm. or more, but averaging 7 or 8 nun. Surface smooth, 
macular of larger zooecia than those of the intermacular spaces, but not conspicuous. 
a Ann. and Mag. Nat. Hist. (5), XIII, 1884, p. 120, pi. 7, figs. 4-4b. 
