304 



2 to 3 mm. apart in which the vestibular are greatly thickened and the 

 zooecia less numerous than in the intermacular area. 



The zooecia are arranged into more or less definite longitudinal rows 

 (13 to 14 in 2 mm.) separated by one or more rows of minute tubuli. The 

 apertures at the surface are mostly elliptical (G to 7 in 2 mm. measured 

 longitudinally) with the longer diameter parallel to the direction of the 

 series. In the maculae and near the non-poriferous margin the apertures 

 are rounded. 



The cross-section shows a single row of median tubuli traversing the 

 mediaJi laminae lengthwise. 



The zooecia in the primitive area lie inclined upward along the median 

 laminae to the inferior hemiseptum. After passing the septa the zooecial 

 tube turns abruptly outward, enters the vestibular area and proceeds 

 almost directly to the surface. An occasional diaphragm, either straight or 

 curved, occurs in some of the zooecia. 



Occurrence : Lebanon limestone ; Big Springs, Rutherford County, Ten- 

 nessee. 



Holotype : 248 — 25. Indiana University. 



Family SticroporcUUlac, Nicklcs and Bassler. 



This family differs from Ptylodictyonidae mainly in that the zoarium is 

 not articulated, but grows upward from, and is continuous with, a spread- 

 ing base. 



Genus StictoporcUa Ulrich. Genotype: Stictoporella interstincta Ulrich. 



Stictoporella Ulrich, Jour. Cincinnati Soc. Nat. Hist., 5, 1882, pp. 152, 

 169. Miller, N. A. Geol. Pal., 1889, p. 325. Ulrich, Geol. Surv. Illinois, 8, 

 1890, p. 394; Geol. Minnesota, 3, 1893, p. 179. Pocta, Syst. Sil. Centre 

 Boheme, 8, pt. 1, 1894, p. 14. Ulrich, Zittel's Textb. Pal. (Engl, ed.), 189G, 

 p. 279. Simpson, 14th Ann. Kept. State Geol. New York for 1894, 1997, 

 p. 535. Nickles and Bassler, Bull. U. S. Geol. Surv., 173, 1900, p. 46. Gra- 

 bau and Shimer, N. A. Index Fossils, 1. 1907, p. 157. Cumings, 32d Ann. 

 Rept. Dept. Geol. Nat. Res. Indiana, 1908, p. 756. Bassler, Bull. U. S. 

 Nat. Mus., 77, 1911, p. 127 ; Zittel-Eastman Textb. Pal., 1913, p. 345. 



Micropora Eichnald (not Gray, 1848), Bull. Soc. Nat. Moscow, No. 4, 

 1855, p. 457 ; Lethaea Rossica, 1, 1860, p. 393. 



Zoarium, branching, cribose, or leaflike, from an expanded base. Zooecia 

 with primitive portion tubular, usually long, generally without hemisepta, 

 the inferior one only occasionally present. Apertures at the bottom of a 

 wide, sloping vestibule. Thick-walled mesopores, with true diaphragms 

 wanting occur between the apertures and line the margin of the zoarium. 



Stictoporella crihrilina n. sp. Plate XIV, Figs. 4-7. Zoarium consists of 

 a cribrose, bifloliate expansion from an extended base. The anastomosing 

 branches average .7 mm. in thickness and .5 to 1 mm. in width. The fenest- 

 rules are small oval openings .75 to 1.5 mm. in greatest diameter and irregu- 

 larly distributed. 



