BRYOZOA. 207 
Phylloporinida.] 
also in rows encircling the stems. Apertures rounded or broad-oval, slightly oblique, 
about 0.15 mm. in diameter, separated lengthwise by intervals a little greater than 
their diameters, with seven or eight in 2.5 mm.; peristomes thin, strongest and 
most elevated posteriorly. Interspaces striated, occasionally rising into strong ridges 
which separated the longitudinal ranges of zocecial apertures for a short distance. 
The smaller, subcircular apertures and differently marked interspaces, distin- 
guish this species from N. ovalis. In N. granosa the zocecial apertures are much nar- 
rower and alternately arranged, while the interspaces are papillose. NV. alternata 
Ulrich, from a similar horizon in southern Illinois, has the zoccial apertures 
arranged in quincunx, and differs in other obvious particulars. 
Because of the rounded zocecial apertures and their prevailing mode of arrange- 
ment, the branches of this species sometimes resemble those of Protocrisina exigua 
Ulrich, a cyclostomatous form that is associated with it at Cannon Falls. This 
resemblance may prove a little troublesome when the surface of the Nematopora is 
slightly abraded so that the striation of the interspaces is obscured. In all cases, 
however, when the specimens can be observed free from the matrix they may be 
distinguished at once by the fact that in the Nematopora the surface is celluliferous 
on all sides, while in the Protocrisina one side of the branches is striated longitu- 
dinally and without zocecial apertures. 
Formation and locality.—Galena shales, near Cannon Falls, Minnesota, where it is associated with 
the preceding species and many other small Bryozoa. Prasopora insularis Ulrich, is the commonest and 
most characteristic fossil of this horizon. 
Family PHYLLOPORINIDA, Ulrich. 
The genera comprised in this family, Phylloporina, Drymotrypa and Chainodictyon, 
are not very important in the way of specific and individual representation, but viewed 
from a biologic standpoint they are decidedly interesting. This interest attaches 
chiefly to the fact that they furnish excellent examples of what have been very aptly 
termed “comprehensive types.” 
A careful investigation of the internal structure of the various species of Phyllo- 
porina leads us to the conviction that at some time prior to the age of the Chazy 
there existed Bryozoa that combined characters which, during subsequent periods, 
became separately specialized and characteristic of widely different groups of fami- 
lies. Take, for instance, P. trentonensis Nicholson, sp., or P. sublaxa, P. halli and P. 
corticosa of the present work. In all of these remarkable forms we are reminded 
very strongly of typical T’repostomata, the subangular zocecial tubes, their long “‘im- 
mature” region, diaphragms, mesopores and acanthopores being, all of them, char- 
acteristic of species of that suborder. 
