290 
Nicholsonella Ulrich, Geol. Surv. Illinois, 8, 1890, pp. 374, 421. Miller, N. A. 
Geol. Pal., 1889, p. 313. Ulrich, Geol. Minnesota, 3, 1893, p. 318; Zittel’s 
Textb. Pal. (Engl. ed.), 1896, p. 276. Simpson, 14th Ann. Rept. State Geol. 
New York for 1894, 1897, p. 590. Nickles and Bassler, Bull. U. 8S. Geol. 
Survy., 173, 1900, p. 34. Bassler, Bull. U. S. Geol. Surv., 292, p. 37. Grabau 
and Shimer, N. A. Index Fossils, 1, 1907, p. 136. Cumings, 32d Ann. Rept. 
Dept. Geol. Nat. Res. Indiana, 1908, p. 751. Bassler, Bull. U. S. Nat. Mus., 
77, 1911, p. 224; Zittel-Eastman Textb. Pal., 1913, p. 334. 
Zoaria consist of flattened branches, fronds or laminations. Mesopores 
are usually numerous. The walls of both zocecia and mesopores are tra- 
versed longitudinally by minute tubuli, which appear at the surface as gran- 
ular acanthopore-like structures. A calcareous deposit in the outer zone 
obscures the walls of the mesopores. Because of the granular structure 
which is present in the outer zone of specimens of this genus it has been 
referred to the family Constellaridae. 
Nicholsonella frondifera. n. sp. Plate VII, Figs. 6-7. The zoarium consists 
of wide flattened frond-like growths, 80 to 50 mm. wide, from the margin of 
which rise branches 15 to 20 mm. wide that frequently divide and anasto- 
mose. The thickness of the branches varies from 5 to 11 mm. The highest 
specimen seen measured 10 cm. 
The surface is even and granulose. The zooecia of the mature zone are 
circular, completely separated by mesopores. Five to seven large, distinct, 
granular masses (cross-section of longitudinal tubuli in tangential sections) 
surround each zooecium. 
The internal structure as seen from the longitudinal section is similar to 
Nicholsonella pulchra with the exception that diaphragms are more num- 
erous in the mesopores of the mature region and the longitudinal tubuli 
are larger, fewer, and more clearly defined in N. frondifera. 
The habit of growth in addition to the different internal characters sep- 
arates NV. frondifera from N. pulchra, its associated species. 
Occurrence: Pierce limestone, Murfreesboro, Tennessee. 
Ridley limestone: Almaville; 2 m. W. of Lascasses; South side of 
Marshall Knob; 24% m. NW. of Salem; Rutherford County, Tennessee. 
Lebanon limestone: Big Springs, Rutherford County, Tennessee. 
Holotype: 54043 U. S. Nat. Mus. 
Paratypes: 244-3, 4,5. Indiana University. 
Family Halloporidae Bassler. 
(Calloporidae Ulrich) 
This family includes trepostomatous bryozoans with ramose, subfron- 
descent, massive or discoidal zoaria, having zooecial tubes that are thin- 
walled, attaining full size slowly, tabulated in the attenuated proximal 
end, and separated more or less completely by angular mesopores. Acan- 
thopores are wanting. 
Genus Hallopora Bassler. Genotype: Callopora elegantula Hall. Cal- 
lopora Hall, Amer. Jour. Sci., ser. 2, vol. ii, 1851, p. 400; Pal. New York, 2, 
1852, p. 144. Nicholson, Pal. Province, Ontario, 1874, p. 61; Geol. Mag., N. 
