287 



Mosopores are fow and soldoin olisorvod in simllow (anjiontial so<'ti<ais 

 (•f old spec'inions. 



Acantlioporos are iiuinerous, 'J. t(i (> about a /noociuin, and of (wo sizes. 



Ill the tangential seetions the wjills appear amalgamated and a distinci 

 ( rennlation is observed from the longitudinal section in the axial rejjion. 



niahpraynis are few and luuMiually distributed in the immaiure zone 

 and (lose set in the mature where 2 to 4 cross the tube in the si)ace of one 

 tube diameter. 



The method of srowdi of this species distin,i;uishes it from the associated 

 forms. 



Occurrence: Ridley limestone, 214 niiles northwest of Salem, Uutiierford 

 County, Tennessee. 



Holotype : 245-6, 10. Indiana University. 



flonis Hctcrotnjpa yichnlsan. Genotype: Monticulipora frondosa 

 D'Orbi.uny. Heterotrypa (in part) Nicholson, Pal. Tabulate Corals, 1870. 

 p. 25)1 : senus Monticulipora, ISSl, pp. 101, 103. Zittel, Handb. Pal.. 1, p. G15. 

 inrich. Jour. Cincinnati Soc. Nat. Hist.. 5, 1882. p. 155 ; ibid., G, 1883, p. 83. 

 Foord. Contr. Micro-Pal. Cambro-Sil.. 1883, p. 20. Ulrich, Jour. Cincinnati 

 Soc. Nat. Hist.. 6, 1883, pp. 83-85. Roemer. Leth. geog.. pt. 1. I.(>tli. Pal.. 

 1883, p. 471. Rominger. Amer. Geol.. 0. 1890. pp. 114. 119. I'lrich. Ceo!.. 

 Surv. 111.. 8, 1890. pp. 371. 413; Geol. Minnesota. 3, 1893, p. 267. Zittel's 

 Textb. Pal. (Engl, ed.), 1896. p. 104. Ulrich, Zittel's Textb. Pal. (Engl, ed.), 

 1896, p. 273. Simpson, 14th Ann. Rept. State Geol. New York for 1894, 1897, 

 p. 579. Nickles and Bassler, Bull. U. S. Geol. Surv., 173, 1900, p. 31. Cum- 

 ings, Amer. Geol., 29, 1902, p. 199. T'lrich and Bassler, Smith. Misc. Coll., 

 Quart.. 47, 1904, pp. 24, 25. Bassler. Zittel-Eastman Textb. Pal.. 1913, p. 333. 



Zoarium erect (ramose or) frondescent : acanthopores of one kind; small; 

 mesopore.s varying in number, generally abundant, sometimes wanting 

 almost entirely. With the addition of the words enclosed in parenthesis the 

 description of the genus is taken from the "Revision of the Paleozoic Bry- 

 ozoa" by Ulrich and Bassler. 



Heterotrypa patera 11. sp. Plate VI. Figs. 5-6. Zoarium ramose, about 5 

 to 10 mm. in diameter. Surface is smooth, with small maculae composed 

 of mesopores, surromided by zooecia slightly larger than the average; about 

 4 in Vi sq. cm. 



Tangential sections show the zooecia to be subcircular and thick-walled. 

 A very thick ciugulum consisting of laminated secondary tissue, surrounds 

 each aperture. A thin dark line separates the cingulum from the true zooe- 

 cial wall which forms an angular boundary between the zooecia and appears 

 tinely granular, light colored and amalgamated. The acanthopores are 

 small, with a distinct, minute central lucid spot and an indetinite outer 

 boundary ; 5 to 10 among 10 zooecia. 



The zooecia in the axial region are crossed by diaphragms from 1 to 3 

 tube-diameters apart. From tiie inunature region the zooecial tul>es proceed 

 outward in a gradual curve, increasing suttieiently in the peripheral zone to 

 cause the zooecia to open periK'iidicularly at the surface. The walls and 

 cingulum increase in thickness from the early mature region to the peri- 



