298 
The zoecia are subpentagonal, thin-walled and completely separated by 
mesopores ; 4 to 5 occur in 2 mm. 
The mesopores are only slightly smaller than the zooecia, of more irreg: 
ular shape, thinner walled and usually six-sided as seen in the tangential 
section. In the younger stages they are zooecial-like, with few or no dia: 
phragms, becoming smaller in the mature region and crossed by 2 to 8 dia- 
phragms in the distance of their own diameter. The smaller mesopores are 
distinctly beaded. The zooecia increase in size with age, and have few 
and irregularly spaced diaphragms; one to two in the primitive portion, 
and rare or absent in the peripheral zone.: The acanthopores are large, 
thin-walled and have a well developed central lucid area. They occur at 
the angles of the zoecia and mesopores and are a little more numerous than 
the zoecia. 
The characters of the tangential section separate this species from any 
described Stromatotrypa. 
Occurrence: Pierce limestone, at the ford 14% mile southeast of Black- 
man, Rutherford County, Tennessee. 
Holotoype: 245-16. Indiana University. 
ORDER CRYPTOSTOMATA VINE. 
The definition of the order, as given by Ulrich in the English edition of 
Zittel’s Textbook of Paleontology, and again repeated by Bassler in the 
Zittel-Eastman edition, published in 1918, is as follows: 
“Primitive zooecium short, pyriform to oblong, quadrate or hexagonal, 
sometimes tubular, the aperture anterior. In the mature colony the aper- 
ture is concealed, occurring at the bottom of a tubular shaft (‘‘vestibule”), 
which may be intersected by straight diaphragms or hemisepta, owing to 
the direct super-imposition of layers of polypides; vestibular shaft sur- 
rounded by vesicular tissue, or by a solid calcareous deposit; the external 
orifice rounded. Marsupia and avyicularia wanting.” 
Family Ptilodictyonidae Ulrich. 
Zoarium pbifoliate, composed of two layers of zooecia, grown together 
back to back, forming leaf-like expansions, or compressed branching or in- 
osculating stems, that are usually jointed, at least at the base; mesotheca 
without median tubuli; zooecia usually have hemisepta and semielliptical 
orifices ; apertures usually ovate, surrounded by a sloping area or a distinct 
peristome; vestibules separated by thick walls. 
Genus Graptodictya Ulrich. Genotype: Ptilodictya perelegans Ulrich. 
Graptodictya Ulrich, Jour. Cincinnati Soc. Nat. Hist., 5, 1882, pp. 151, 165. 
Miller, N. A. Geol. Pal., 1889, p. 307. Ulrich, Geol. Surv. Illinois, 8, 1890, 
p. 393. Procta, Syst. Sil. Centre Boheme, 8, pt. 1, 1894, p. 14. Simpson, 14th 
Ann. Rept. New York State Geol. for 1894, 1897, p. 541. Nickles and Bass- 
ler, Bull. U. 8S. Geol. Sury., 173, 1900, p. 46. Cumings, 32d Ann. Rept. Dept. 
Geol. Nat. Res. Indiana, 1908, p. 747. Bassler, Bull. U. S. Nat. Mus., 77, 
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