116 THE PALEONTOLOGY OF MINNESOTA. 
[Stomatopora. 
matter, the former in their mature or ultimate development, are much nearer Berenicea 
(Lamouroux, Haime, Zittel and others ; Diastopora of Busk and other British authors). 
Sharply defined genera are an impossibility in nature. She follows paths altogether 
too intricate to be expressed in a system of classification. The best result that we 
can obtain must be a happy medium between convenience and natural affinity. Con- 
venience, and stability as well, are surely sacrificed when we throw together a number 
of genera and then divide the composite genus, that has now been made to assume 
the rank of very nearly a family, into sections of questionable utility that no one is 
obliged to recognize, because they have no established validity in any system of 
classification. Is it not better, because it is convenient and saves time, to have it 
understood at once that when one says Stomatopora, he refers to uniserial forms ; 
Proboscina, to forms with similar zowcia but partly immersed and in two or more 
series, and Berenicea, to such as have them forming entire, flabellate, circular or 
irregular crusts ? 
The only change from the arrangement here retained that I am willing to enter 
into, and for which good and probably sufficient reasons can be advanced, is one 
that would drop Proboscina, leaving Stomatopora to stand as at present for the 
uniserial species, and extend Berenicea so as to include the ground now occupied 
by Proboscina. 
STOMATOPORA TENUISSIMA Ulrich. 
PLATE I, FIGS. 6and 7%. 
Stomatopora tenuissima ULRICH, 1890. Jour. Cin. Soc. Nat. Hist., vol. xii, p. 175. 
Original description‘ Zoarium adnate, consisting of frequently branching 
uniserially arranged zoccia. Zocecia exceedingly slender, about seven in 8 mm., 
each from 1.0 to 1.5 mm. long, usually increasing very gradually from the proximal 
end, where the diameter is about 0.04 mm., to near the slightly bulbous anterior or 
upper end, which varies from 0.11 to 0.18 mm.in diameter. Aperture circular, small, 
about 0.05 mm. in diameter, situated very near the anterior end of the zoccium. 
“This and S. turgida illustrate the extremes of difference in shape and size of 
the zocceia of Stomatopora so far noticed. SS. tenwissima is closely related to S. prout- 
ana Miller, but its zocecia are much longer. Miller’s species, with scarcely any 
modification, ranges from low in the Trenton (Birdseye limestone) to the top of the 
Hudson River group. 
Formation nad locality. Toward the top of the Utica horizon of the Hudson River group at Cincin- 
nati, Ohio, 150 to 175 feet above low water mark in the Ohio river. . 
