NORTH AMERICAN EARLY TERTIARY BRYOZOA. 839 
Distance between the lines 0.24-0.26 mm. 
Width of the lines 0.20 mm. 
l easui ements. Diameter of the peristome 0.10-0.12 mm. 
Maximum width of the branches 1.25 mm. 
Variations. — The polymorphism of this species is unprecedented. If the 
number of the specimens found had not permitted the discovery of the intermediate 
forms, it might have appeared that many new species were represented. An inter- 
esting variation is that shown by the young branches; the tubes do not bear any 
vacuoles ; their frontal is concave, bordered laterally, and of a microscopic structure 
analogous to that of the other Cyclostomata. 
The longitudinal section shows very numerous vacuoles. The successive 
lamellae have no regularity; they appear to be formed by very thick walls of 
tergopores irregularly branched and entangled. This is therefore only one aspect 
of lamellar structure. In transverse section these pseudo-lamellae are still more 
irregular; they appear to result from the juxtaposition of the tergopores arranged 
parallel to the basal lamella. 
The tangential section of the dorsal shows that the vacuoles perforate a sort 
of olocyst with large elements. 
The abrasion of the dorsal vacuoles and of the basal lamella shows that in the 
interior the tubes have the fusiform appearance and are arranged as in the other 
free Cyclostomata having only one cellular face. 
The zoarium is supported by an expanded base. Only a single specimen with 
the base has been found and we have not been able to discover the ancestrula by 
successive sections. 
Affinities. — This species differs from Polyascosoecia cancellata Re uss, 1847 
(not Goldfuss), in its fascicles which are quite close to the median crest. 
It differs from Polyascosoecia foraminosa Reuss, 1865, in its smaller vacuoles 
and in its fascicles not distant from the median crest. 
This may possibly be Polyascosoecia sub cancellata Manzoni, 1877, but that 
author has neglected to figure the anterior face of the zoarium, the aspect of which is 
unknown to us. 
Occurrence. — Middle Jacksonian: Rich Hill, 5£ miles southeast of Knoxville, 
Crawford County, Georgia (very abundant) ; Baldock, Barnwell County, South 
Carolina (common) ; 17 miles northeast of Hawkinsville, Georgia (common) ; 3^ 
miles south of Perry, Georgia (very abundant) ; 34 miles north of Grovania, 
Georgia (common) ; one-half mile southeast of Georgia Kaolin Co. mine, Twiggs 
County, Georgia (very common), 12 miles southeast of Marshallville, Georgia 
(abundant); Eutaw Springs, South Carolina (rare); 18 miles north of Wrights- 
ville, Johnson County, Georgia (common) ; 14 miles southeast of Lilly, Dooly 
County, Georgia (common). 
This species exists in almost all the localities of the middle Jacksonian, although 
it has not yet been found at this horizon at Wilmington, North Carolina. 
Cotypes. — Cat. Nos. 65333, 65334, U.S.N.M. 
