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BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 
1S62. Lunulites distans Gabb and Horn, Monograph of the Fossil Polyzoa of the Secondary 
and Tertiary formations of North America, Journal Academy Natural Sciences, 
Philadelphia, ser. 2, vol. 5, p. 119. 
1890. Lunulites distans DeGregorio, Monographie de la Faune Eocenique de l’Alabama et 
surtout de eelle de Claiborne de l’Etage parisien, Annales de Geologie et de 
Paleontologie, Livraisons 7, 8, p. 250, pi. 42, fig. 29. 
185S. Lunulites contigua Emmons, Geological Survey North Carolina, Paleontology, p. 311, 
figs. 250, 251 (not L. contigua Lonsdale, 1S45). 
Description . — The zoarium is a large, convex Lunulites, on which the rows of 
zooecia alternate with rows of vibracula. The zooecia are disposed in radial and 
circular rows, and are distinct, elongate, hexagonal, or ogival. The cryptocyst is 
not distinct from the mural rim; it is deep, flat, very finely granulated; more de- 
veloped in the small than in the large zooecia; the opesium is elongate, ogival, 
with a slightly concave proximal border. The ovicell reposes on the distal wall ; it is 
a small convexity, distinct from the mural rim. The vibraculum is elongated, narrow, 
lozenge-shaped, symmetrical, provided with two lateral condyles. The interior of 
the zoarium is hollow ; the zooecia are devoid of basal walls and are wide open 
into the zoarial cavity. The inner side is a thin calcareous or chitinous pellicule 
provided in the interior with numerous tuberosities. The ancestrula is a zooecium 
identical with the others. The ancestrular zooecia are sometimes hydrostatic or 
radicular. 
Variations . — The zoarium generally is of large dimensions (figs. 3, 4, 5). 
To insure the upright position it is necessary to have an extensive hydrostatic 
system, because lime is much heavier than the water. This is the reason for the 
absence of all fibrous tissue. 
This exceedingly light apparatus is very fragile and breaks very easily, for en- 
tire zoaria are never found. In calcareous sediments the mud fills up the internal 
cavity and preserves the fragile lamella which covers the zoarium. On these rather 
common fossils, it may be noted that the inner side (fig. 18) of this lamella bears 
numerous tuberosities. The radial rows of zooecia are separated by vertical parti- 
tions supporting the frontal cryptocyst which has been worn away on account of 
its fragility, although it is easy to reconstruct it in the mind’s eye (figs. 1-5). 
The inner side of the zoarium is extremely fragile. Upon the supposition that 
one of our specimens is a mold of the exterior, an impression of it in wax (fig. 19) 
gives the external aspect of the inner side, but we have no confirmation of this 
structure from actual specimens. Quite frequently the zoaria are found with a 
large cavity representing the place where some incrusting bryozoan or other 
organism has strengthened the fragile inner side. . 
We have found some zooecia with a polypiclian convexity (fig. 7) ; the parietal 
muscles are therefore attached to the cryptocyst. 
The size of the zooecia is quite variable and must depend on the size of the 
ancestrula and the convexity of the zoarium. Figure 11 illustrates the rare case 
of a gigantic ancestrula surrounded by large zooecia; generally the zoarium com- 
mences with radicular zooecia (fig. 8), a zone of small zooecia appears next (figs. 
