290 



Nicholsonella Ulrich, Geol. Siirv. Illinois, S. 1890, pp. 374. 421. Miller, N. A. 

 Geo!. Pal., 18S9, p. 313. Ulrich, Geol. Minnesota, 3, 1893. p. 313; Zittel's 

 Textb. Pal. (Engl, ed.), 1896, p. 276. Simpson. 14th Ann. Kept. State Geol. 

 New York for 1894, 1897, p. 590. Nicklos and Bassler, Bull. U. S. Geol. 

 Surv., 173, 1900, p. 34. Bassler, Bull. TJ. S. Geol. Surv., 292, p. 37. Grabau 

 and Shimer, N. A. Index Fossils, 1, 1907, p. 136. Cumings, 32d Ann. Kept. 

 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 zooecia and mesopores are tra- 

 versed longitudinally 1)y 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 frondifcra. n. sp. Plate VII. Figs. 6-7. The zoarium consists 

 of wide flattened frond-like growths, 30 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 

 NicholsoneUa 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 deflned in N. fronddfera. 



The habit of growth in addition to the different internal characters sep- 

 arates N. frondifcra fx'om N. pulchra, its associated species. 



Occurrence : Pierce limestone, Murfreesboro, Tennessee. 



Ridley limestone : Almaville ; 2 m. W. of Lascasses ; South .side of 

 Marshall Knob ; 2i/^ m. NW. of Salem ; Rutherford County, Tennessee. 



Lebanon limestone : Big Springs, Rutherford County, Tennessee. 



Holotype : 54043 IT. S. Nat. Mus. 



Paratypes : 244-3, 4, 5. Indiana University. 



Familji IJalloporidac Bassler. 

 ( Calloporidae TTlrich ) 



This family includes trepostomatous bryozoans with ramose, subfron- 

 de.scent, 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. 



