Catal 
American Paleozoic Bryozoa. 259 
The relations of Zrematopora are perhaps nearer Atactoporella than 
to any other genus of Paleozoic Bryozoa. ‘Taking such a species as 
A. newportensis, Ulrich, we find a decided superficial resemblance 
to 7. tuberculosa, Hall. However, when more critically examined, they 
are found to differ in the following characters: The tube-walls in 
Atactoporella are always more or less inflected, and the spiniform tubuli 
more numerous, the true zoccial-tubes are provided with both cystoid 
and horizontal diaphragms, while in the interstitial tubes the straight 
diaphragms are numerous, and the tube-cavity is never constricted at 
the point of their occurrence. On comparing the genus with Hall’s 
Callopora, we find that while in Trematopora the zocecial apertures 
are always open, and the interstitial cell-mouths closed by a minutely 
perforated pellicle, the opposite is the case in Callopora, the proper 
zoecia being commonly closed by centrally perforated opercula, and 
the interestial cells alwaysopen. ‘The most striking internal difference 
lies in their tabulation, diaphragms being very numerous in both kinds 
of tubes in Callopora, and exceptionally few in Trematopora. ‘That 
the character and limits of the genus may be the more fully understood, 
a full diagnosis of the type sp cies is here appended, and followed by 
the descriptions of two congeneric species that appear to be new. 
TREMATOPORA TUBERCULOSA, Hall (Pl. XIII, figs. 2, 2a, 26). 
Trematopora tuberculosa, Hall, Pai. N. Y., vol. ii., p. 149, figs. la-lg, Pl. XL. A. 
Zoarium irregularly ramose, branches stout, generally flattened. 
Surface at intervals of from .12 to .15 ofan inch, measuring from center 
to center, elevated into rounded monticules, varying in height in 
different specimens. True cells with oval-apertures, surrounded by a 
more or less distinct peristome, which carries a variable number, rarely 
more than two, of rather large spiniform tubuli; longest diameter of 
aperture about ;4,th of an inch. Intercellular spaces of very variable 
width, the true cells being often in contact on one side, and separated 
from each other on another side, sometimes more than their diameter; 
cells therefore arranged in more or less interrupted series, in which, 
across their shorter diameter, from cight to eleven may be counted in 
the space of .1 inch, and from seven to nine in the same space measur- 
ing across their longer diameter. The really large and numerous in- 
terstitial cells having their apertures usually closed by a pellicular 
covering, rarely present stronger evidences of their presence than 
unequal shallow depressions between the peristomes of the true cells; 
they are, perhaps, most readily detected on the monticules, where the 
