296 
slight thickening of the walls, and the origination of an abundance of beaded 
mesopores mark the initial periphery zone. A few thin diaphragms occur 
in some of the zoecial tubes in the mature region and in others they are 
absent. A distinct median lamina separates the zoecial walls. 
Occurrence: Pierce limestone, Murfreesboro, Tennessee. 
Holotype: 44708, U. 8. Nat. Mus. 
Genus Diplotrypa Nicholson. Genotype: Fayosites petropolitanus Pan- 
der. Diplotrypa Nicholson, Pal. Tab. Corals, 1879, pp. 101, 155. Ulrich, 
Jour, Cincinnati Soe. Nat. Hist., 5, 1882, p. 153. Foord, Contr. Micro-Pal. 
Cambro-Sil., 1883, p. 13. Roemer, Leth. geog., 1, Leth, Pal., 1883, p. 472. 
Miller, N. A., Geol. Pal., 1889, p. 187. Ulrich, Geol. Surv. Tlinois, 8, 1890, 
pp. 378, 457. Rominger, Amer. Geol., 6, 1890, pp. 116-119. Ulrich, Geol. Min- 
nesota, 3, 1898, p. 285; Zittel’s Textb. Pal. (Hngl. ed.), 1896, p. 275; also 
(not Ulrich) p. 104 (in part). Nickles and Bassler, Bull. U. 8S. Geol. Sury., 
173, p. 36. Bassler, Bull: U. S: Geol. Sury., 292, 1906, p. 47; Zittel-Hast- 
man Textb. Pal., 1913, p. 338; Bull. U. S. Nat. Mus., 77, 1911, pp. 312, 318. 
Callopora (not Hall) Dybouski, Du Chaetetiden d, Ostb. Silur.-Form., 1877, 
p. 106. 
The zoarium of Diplotrypa is massive, or discoid and generally free, con- 
sisting of large prismatic zoecial tubes with thin walls. Mesopores are al- 
ways present, but variable in number and size. Complete, horizontal dia- 
phragms are present in both the zoecia and mesopores. Acanthopores are 
wanting. 
Diplotrypa catenulata n. sp. Plate X, Figs. 6-7. Zoarium massive, dis- 
coid, 2% to 4 em. in diameter and % to 2% em. in thickness. The base is 
circular, covered with thin concentrically wrinkled epithelium. The zoecial 
apertures are large and polygonal; 4 to 4% in 2 mm. Mesopores are few 
and of various shapes and sizes. 
In the longitudinal section the tube-walls are thin and beautifully crenu- 
lated. The mesopores originate as catenated chambers, enlarging and de- 
veloping into tubes similar to zoecia as they approach the periphery. The 
diaphragms of the zoecia are spaced from 2 to 4 tube diameters apart in 
the immature region and about one tube diameter apart in the mature zone. 
In the mesopores diaphragms are present at the constrictions. 
The form of the zoarium, the large zoecia, crenulated walls and irregu- 
larly beaded mesopores are a group of characters that distinguish this 
species from any other species of the genus. 
Holotype: 44658 U. S. Nat. Mus. 
Oceurrence: Pierce limestone, Murfreesboro, Tennessee. 
Genus Stromatotrypa Ulrich. Genotype: Stromatotrypa orata Ulrich. 
Stromatotrypa Ulrich, Geol. Minnesota, 3, 1895, p. 501. Miller, N. A. Geol. 
Pal., 2d App., 1897, p. 758. Nickles and Bresler, Bull. U. 8. Geol. Sury., 173, 
p. 35. Grabau and Shimer. N. A. Index Fossils, 1, p. 157. 
Zoaria consist of laminated expansions growing upon foreign bodies, and 
of globuler: masses in which the zoecial tubes radiate from a small base 
covered with epitheca. The zoecia have thin walls and are crossed by few 
