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Zoarium consists of parasitic and laminate expansion which in some spe- 
cies rises into domed or globular masses. The wall structure resembles the 
Heterotrypidae more than the Monticuliporidae. The acanthopores are well 
developed and sharply defined. The cystiphragms, which appear as curyed 
diaphragms, form the basis for the assignment of the genus to the family 
Monticuliporidae. 
Orbignella nodosa. n. sp. Plate V, Figs. 1-2. The zoarium forms small 
and large incrusting expansions, that rise into nodular masses of irregular 
forms and sizes, by superposition of layers; nodules are unequally distrib- 
uted. Slabs have been collected on which there are numerous colonies that 
are contiguous and overlap one another, forming an incrustal covering 
of many square inches. The nodules vary in height from .5 mm. to 10 mm., 
with a corresponding variation in width. 
The surface is even; twenty-four maculae of large zooecia occur in one 
sq. em. 
The zooecia are polygonal, and have relatively thick wall; 8 to 9 occur 
in 2 mm. Mesopores are absent. Acanthopores are about as numerous as 
the zooecia, located at the tube angles, and of large size, causing slight 
inflection of the zooecial walls in most cases. 
The zooecial tubes of each laminar expansion are about .7 mm. long, with 
8 to 4 horizontal or from 1 to 3 cystoid diaphragms in the space of one tube 
diameter. 
The nodular zoarium, lack of monticules, and more numerous cystoid dia- 
phragms distinguish the species from Obignyella weatherbyi. Orbignyella 
lamellosa has large zooecia, less curved diaphragms, and much longer 
zooecial tubes than O. nodosa. The large acanthopores and zoarial forms 
of O. nodosa are distinet differences which separate it from O. swblamellosa. 
Occurrence: Lebanon limestone, Big Springs, Rutherford County, Ten- 
nessee. 
Holotype, 248-16. Indiana University. 
Orbignyella multitabulata. un. sp. Plate V, Figs. 3-4. Zoarium, lamni- 
ated, depressed, conical domes, rising from a wide base. The lower surface 
of the mass is covered with a wrinkled epitheca. The type specimen is 9.5 
em. in diameter and 2.5 em. high. The surface is smooth, with inconspicu- 
ous clusters of large zoecia. 
Mesopores are very few, occurring in the maculae only. The zoecia are 
angular, thin-walled; 8 to 8% in 2mm. Large well developed acanthopores 
with distinct lumen are present at most every tube angle. 
The zooecial tubes of a single lamina are 1 to 38 mm. long, crossed by 4 
to 5 horizontal diaphragms in the space of one tube diameter. Cystoid, 
curved or infundibular diaphragms occur in every tube. 
The crowded horizontal diaphragms, thickness of laminae, large acan- 
thopores, and manner of zooecial growth, are a combination of characters 
not found in any other species of the genus yet described. 
Occurrence: Pierce limestone; in sink hole at Almaville, Rutherford 
County, Tennessee. 
