BRYOZOA. 217 
Monticulipora.] 
The principal and almost infalliable distinguishing peculiarity of the family is 
the cystiphragm. As a rule these structures form continuous series in the zocecial 
tubes, and in all such cases their nature is at once determinable in either vertical 
or tangential thin sections. But in the genera Monticulipora and Mesotrypa they are 
often modified so that they might be mistaken for simple, oblique or slightly curved 
diaphragms. On plate XV figures 8 and 9 illustrate the latter, while of the usual 
form of the cystiphragms many examples are figured on plates XV to XIX. 
Genus MONTICULIPORA, d’Orbigny. 
Monticulipora, d’ORBIGNY, 1850. Prodr. de Paleont., t. i, p. 25. ; 
Monticulipora (part.), N1cHoLson, 1879. Struct. and Affin. of the Pal. Tabulate Corals, p. 269. 
Peronopora (part.), NICHOLSON, 1881. “The Genus Monticulipora,” p. 215. 
Monticulipora, ULRicH, 1882, Jour. Cin. Soc. Nat. Hist., vol. vy, pp. 153 and 282; 1890, Geol. Sury. I11., 
vol. viii, pp. 370 and 407. 
: Zoarium massive, lobate, subramose, laminar, incrusting, or frondescent. Sur- 
face usually tuberculated, sometimes even. Monticules closely arranged, usually 
conical, often elongated or compressed. Zocecia polygonal, generally rather small, 
with thin and, internally, peculiarly granulose. walls. Mesopores few, generally 
absent entirely. Cystiphragms present in the zocecial tubes, both in the axial and 
peripheral regions of the zoarium, usually in continuous series, but often isolated. 
Acanthopores small, more or less numerous. 
Type: M. mammulata VOrbigny. 
As now restricted this genus embraces but a small part of the incongruous ma- 
terial for which the genus was a receptacle from the day it was established. Still, 
no less than eighteen species having the essential characters of M/. mammulata, all 
of them Lower Silurian save one, are known to me. The earliest of these is from 
the Birdseye limestone, and several belong to the Trenton proper; but it is in the 
Hudson River rocks that the genus has its strongest development. So far the genus 
is not known in Upper Silurian deposits, and it is possible that all its species became 
extinct at the close of the Lower Silurian. If that should prove to be true the J. 
winchelli Ulrich, described from the Hamilton of Michigan, could not be retained as 
a true member of the genus, since its line of development would necessarily be 
different. 
