180 THE PALEONTOLOGY OF MINNESOTA. 
[Stictoporella. 
Tangential sections of favorably preserved specimens show that both the zocecia ~ 
and mesopores are separated from each other by a sharply defined line of minute 
pore-like dots. True median tubuli and diaphragms wanting. 
Type: S. interstincta Ulrich. Range, Lower Trenton to Chester. 
For remarks on the relations and systematic position of this genus see ante p. 162. 
The range of zoarial diversity allowed in this genus is unusually comprehensive. 
Perhaps it is too much so, and that the cribrose species ought to be distinguished 
generically. Most certainly they look very different from the others and are, I grant, 
as much entitled to generic separation as Clathropora, Hall, Cosciniwm, Keyserling, 
and other genera that might be mentioned, all differing from related genera chiefly 
or solely in the cribrose character of the zoaria. Though inclined to favor a sepa- 
ration, I have decided to leave them with Stictoporella for the present. 
CLASSIFICATION OF AMERICAN SPECIES. 
Section a: zoarium branching. 
Stictoporella interstincta Ulrich, Utica horizon, Cincinnati group, Kentucky. 
S. angularis Ulrich, base of Trenton shales, Minnesota. 
S. angularis var. intermedia Ulrich, base of Trenton shales, Minnesota. 
S. dumosa Ulrich, Trenton shales, Minnesota. 
S. rigida Ulrich, Trenton shales, Minnesota. 
Section 6: zoarium wide, leaf-like, with macule. 
Stictoporella frondifera Ulrich, base of Trenton shales, Minnesota. 
S. ? basalis Ulrich, Keokuk group, Illinois, Iowa. 
S. ? undulata Ulrich, Chester group, Kentucky, Ilinois. 
Section c: zoarium cribrose. 
Stictoporella cribrosa Ulrich, middle Trenton shales, Minnesota. 
?Clathropora flabellata Hall, Trenton, Wisconsin. 
Stictoporella proavia (Coscinium proavium Billings, ? Hichwald), Trenton, Canada. 
S. n. sp.(with smaller meshes than in the others), ‘‘ Pierce” limestone, Tennessee. 
STICTOPORELLA RIGIDA Ulyich. 
PLATE XI, FIGS. 20 and 21. 
Sticloporella rgida ULRICH, 1890. Jour. Cin. Soc. Nat. Hist., vol. xii, p. 188. 
Original description: “ Zoarium a narrow branching, bifoliar stipe. Branches 
flattened, 1.0 mm. or a litle more wide, with straight parallel and sharp margins, 
acutely elliptical in cross-section. Zocecia in seven to nine or ten rows on each face, 
their apertures arranged in very regular longitudinal and diagonally intersecting 
series, with sixteen or seventeen in 5 mm. lengthwise and four in 1 mm. obliquely. 
Apertures elliptical, 0.2 mm. long, half that wide, impressed, the sloping area narrow 
for this genus, and appearing sometimes a little oblique because of a slight elevation 
of the posterior border; those in the marginal rows are directed slightly outward. 
