218 THE PALEONTOLOGY OF MINNESOTA. 
(Monticulipora wetherbyi. 
MONTICULIPORA WETHERBY! Ulvyich. 
PLATE XV, FIGS. 7 and 8. 
Monticulipora wetherbyi ULRICH, 1882, Jour. Cin. Soc. Nat. Hist., vol. v, p. 239, pl. X, flgs. 4-4b: 1889, 
Contri. to the Micro-Paleon. of the Cambro-Silurian Rocks of Canada, 
pt. ii, p. 30. 
Zoarium attached to foreign objects, forming thin crusts or small depressed- 
conical masses. Surface gently monticulose, sometimes nearly even. Zocecia 
polygonal, with very thin walls, the diameter of those of the ordinary size about 
0.25 mm. Clusters of larger cells attaining a diameter of from 0.3 to 0.38 mm. 
occupy the summits and slopes of the monticules, or in the smooth forms are 
scattered over the surface at intervals of about 2.5 mm., measuring from center 
to center. A few small cells (? mesopores) may be detected, especially at the center 
of the monticules, but they are always an inconspicuous feature and being of various 
sizes are probably to be regarded as merely young zowcia. Acanthopores rather 
large and numerous in the original Kentucky types of the species, small and few in 
the northwestern form. 
In longitudinal sections the zocecial tubes have thin walls with the granulose 
structure characteristic of the genus. The transverse partitions, occurring at inter- 
vals of a tube-diameter or more in the lower half of the tubes and little more than 
a third of that distance apart near the surface, seem really to be all of the nature of 
cystiphragms, though frequently appearing in the sections as straight diaphragms. 
In transverse sections the tubes are angular and thin-walled, with strong acantho- 
pores—one at most of the angles—in the Kentucky specimens, and much smaller 
and fewer ones in the Minnesota and Manitoba form of the species. The cystoid 
nature of the diaphragms is generally recognizable in these sections, but the cresentic 
line, which is the unfailing mark of these structures, may not be detected except in 
only a few of the zocecia. 
Formation and locality.—Rare in the Birdseye limestone of central Kentucky. A single example was 
found in the lower limestone at Minneapolis. 'Che species also occurs at St. Andrews, Manitoba. 
Mus. Reg. No. 5967. 
