282 THE PALEONTOLOGY OF MINNESOTA. 
(Callopora goodhuensis. 
between them is almost if not quite impossible. How else can we explain this fact 
than by assuming that the two forms gradually and by almost equal concessions 
approximated in structure ? 
Compared with other species C. angularis will be found to be smaller, with 
smaller and more equal-sided zocecia and fewer mesopores. C. goodhuensis is smaller 
in every respect. 
Formation and locality.—Rather abundant in the upper layers of the middle and in the lower part 
of the upper third of the Trenton shales at various localities in Ramsey, Goodhue and Fillmore counties, 
Minnesota. Common also at many localities in the state where the Galena shales are exposed, and in 
equivalent beds at Decorah, Iowa. 
Mus. Reg. Nos. 7640, 7659, 8067. 
CALLOPORA GOODHUENSIS, ”. Sp. 
PLATE. XXIII, FIGS. 9, 10, 21, 29. 
This also is closely related to C. multitabulata. As a rule the surface is without 
monticules, and they are never prominent, while the average size of the branches is 
less, the average diameter being between 4 and 5 mm. The zocecia are smaller 
especially at the center of transverse sections, their apertures subangular, rather 
oblique in young examples, nearly direct in those full-grown, with twelve or thirteen 
in38mm. Internal characters very similar, excepting that the peripheral region is 
comparatively narrower, being in this respect more like C. ampla. 
Mesopores more numerous and more closely tabulated than in C. angularis. 
The zocecial apertures, on the ether hand, are more direct in that earlier species. 
Formation and locality—Common in the Galena shales at St. Pauland near Cannon Falls, Minnesota. 
Mus. Reg. No. 8111. 
CALLOPORA DUMALIS, ”. Sp. 
PLATE XXIII, FIGS. 1-8. 
Zoarium bushy, attaining a width of 50 mm. or more, consisting of numerous 
small inosculating branches, varying between | and 2.5 mm. in diameter, but with 
1.5 mm. by far the most common size. In young stages the zocecial apertures are 
more or less oblique and ovate, the mesopores rather numerous and some of them of 
large size. In old fragments the latter are fewer and of small size, and the zocecial 
apertures more direct and polygonal. Closures with faint radiating lines; central 
perforation rather small. Measuring diagonally about six zocecia in 1.5 mm. 
Internal characters as shown in figs. 7 and 8. Vertical sections show that while 
diaphragms are rather abundant in all parts they are not excessively crowded in the 
peripheral region. In this respect the species differs from the species grouped about 
C. multitabulata. 
