290 THE PALEONTOLOGY OF MINNESOTA. 
[Batostoma fertile 
latter, I am now fully satisfied, embraces the progenitors of Trematopora, and as the 
relationship seems to be very intimate it may be well to consider the advisability 
of dropping Batostoma in favor of Hall’s older name. The Calloporide, with Aspi- 
dopora removed to the Monticuliporidw, might be united with the Diplotrypide, from 
which, in that case, it would be well to remove Batostoma.* But for the reasons 
stated it was deemed inexpedient to carry out sweeping innovations in the present 
work, and the only excuse for their mention here is that it seemed necessary to 
publish some idea of the lines in which progressing knowledge is likely to modify 
the present classification. Perhaps also to show how well we are acquainted with 
its imperfections. 
BatostoMA FERTILE Ulrich. 
PLATE XXV, FIGS. 1-11. 
Batostoma fertile ULRicH, 1886. Fourteenth Ann. Rep. Geol. Nat. Hist. Surv. Minn., p. 92. 
Zoarium attaining a large size, 50 to 100 mm. in hight, consisting of strong, 
irregularly thickened, more or less compressed branches that divide without regu- 
larity; thickness of branches 5 to 25 mm., width 8 to 30 mm. Zocecial apertures 
varying according to the size and number of the mesopores and the thickness of the 
walls, from polygonal to circular. In some specimens and portions of others meso- 
pores are exceedingly few and the zocecial walls thin and generally in contact at all 
sides; in the majority of examples mesopores are moderately abundant and the 
walls thicker, but the zocecial apertures are still polygonal or at any rate most of 
them subangular. From this, the typical form, we can trace the variations by small 
degrees into a form which, for the sake of reference, may be designated as var. 
circulare. In this the zocecial apertures are almost perfectly circular, enclosed by a 
raised rim or peristome, and largely separated from each other by depressed inter- 
spaces. Often the peristomes are thicker and more distinctly separated from each 
other than is shown in fig. 6. Interspaces occupied by mesopores varying consider- 
ably in size and shape. Their mouths are commonly closed by a calcareous plate in 
which a variously situated rounded opening may be observed. When the preserva- 
tion is unusually favorable the surface of the plate is studded with very minute 
papille representing the terminations of exceedingly small foramina. Acanthopores 
between one and two to each zocecium, but very small and only in rare instances 
distinguishable at the surface. At intervals of 3 or 4 mm. occur clusters of zocecia 
a little larger than the average, and in the center of these usually small substellate 
macule. Between eight and nine of the average zocecia in 3 mm. 
*The f@inilies reconstructed in accordance with the above suggestions would be as follows: CALLOPORID®, Caliopora, 
Diplotrypa, Monotrypa, ? Calloporella; TRemMatToPoRID!, Trematopora, Batostoma,? Hemiphragma, ? Stromatotrypa; CONSTELLAR- 
1p#, Constellaria, Stellipora, Nicholsonella, ? ldiotrypa. 
