118 THE PALEONTOLOGY OF MINNESOTA. 
(Stomatopora. 
circular, direct, with a peristome, about 0.09 mm. in diameter, situated near the ante- 
rior end. Mural perforations minute and but rarely preserved. 
In the Trenton or typical form of this species the zocecia, as a rule, are less swol- 
len and the adnate zoarium divides less frequently than in the better known Cincin- 
nati form. In the latter, therefore, the network is closer, and occasionally the 
growth is so luxuriant that the rows cross each other to such an extent that but 
little space is left between the cells. No distinction, however, can be based upon 
these characters since, when good series of specimens are studied, it is found that 
among those from Trenton localities some have more than commonly swollen and 
crowded cells, while in some of those from the geologically higher localities the 
growth is lax and the zocecia comparatively narrow. 
Formation and lecantyaemrenton group, at Trenton Falls, New York; Ottawa, Canada; Cannon 
Falls, and other localities in Minnesota where the upper third of the Trenton shales are exposed ; Hudson 
River group at Cincinnati, Ohio, (350 to 425 feet above low water mark in the Ohio river), and in the upper 
beds at Richmond, Indiana; Wilmington and Savannah, Illinois, and other localities. 
Mus. Reg. Nos. 5924, 8045. 
STOMATOPORA TURGIDA Ulrich. 
PLATE I, FIGS. 22 and 23. 
Stomatopora turgida UtricH, 1890. Jour. Cin. Soc. Nat. Hist., vol. xii, p. 176. 
Original description.—* Zoarium adnate, consisting of a single branching series of 
zocecia. Zocecia comparatively very large, the anterior half much swollen, rapidly 
tapering posteriorly, with the slender, tubular proximal end inserted beneath the 
turgid anterior end of the preceding zocecium. Five zoccia in 5 mm.; length of 
each zocecium varying from 0.85 to 1.30 mm.; the greatest diameter of the anterior 
half from 0.4 to 0.6 mm. The longest cells are the least turgid, while the shortest 
are the most. Apertures round, bordered by an elevated margin, small, 0.1 mm. in - 
diameter, and situated about one-fourth of the length of the zceocium from its ante- 
rior end. 
“T have a number of specimens of this species, and all consist of comparatively 
few zocecia. Nor do the series of cells in any of them branch often; from which it 
appears that the production of two “gems” was a much less frequent occurrence 
than in the related S. inflata Hall. S. turgida is further distinguished from that and 
all other species of the genus known to me, by the much larger zocecia.” 
Formation and locality.—Upper beds of the Hudson River group at Wilmington, Illinois. 
