544 
BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 
them are not provided with an ascopore. We have as vet collected no segment 
preserving the base, and we are therefore ignorant of the signification of these pores. 
It may be presumed that one pore is intended for the chitinous joint and the other 
for a radicell (figs. 6, 7). 
The tubules in becoming elongated also increase the diameter of the segments 
and the width of the zooecia (figs. 8, 9) ; but this is a very rare variation. The 
peristomiale presents pores a little larger and arranged at the base of longitudinal 
canals. 
The ovicells are large convexities, of which the external apertures (0.20 mm.) 
are much larger than those of the ordinary zooecia (0.12 mm.). 
At the locality near Perry, Georgia, a segment was found with large pores 
and with very thick peristomes, which we think belongs to this species (fig. 10), 
but of this we are not absolutely certain. 
Affinities. — This species differs from Tubucellaria parviporosa in having some- 
what larger pores and much shorter zooecia (Zs=1.10 mm. instead of 1.30 mm.). 
It may be distinguished from Tubucellaria vicksburgica by its smaller frontal 
pores, its shorter zooecia (1.10 mm. instead of 1.40 mm.), and by its system of 
articulation, which does not have a very salient process. 
This species is rather deceiving in its quite variable external aspect. It may 
only be determined with certainty by the aid of micrometric measurements; it is 
the smallest of the American Tubucellaria. 
Occurrence. — Middle Jacksonian: 18 miles west of Wrightsville, Johnson 
County, Georgia (rare) ; 31 miles south of Perry, Georgia (rare) ; one-half mile 
southeast of Georgia Kaolin Co. mine, Twiggs County, Georgia (rare) ; 17 miles 
northeast of Hawkinsville, Georgia (very rare). 
Upper Jacksonian (Ocala limestone) : West bank Sepulga River. Escambia 
County, Alabama (rare). 
Cotypes. — Cat. Nos. 64183-64185, U.S.N.M. 
TUBUCELLARIA VICKSBURGICA, new species. 
Plate 97, figs. 1-16. 
Description. — The zoarium is articulated, composed of large, long, cylindrical 
segments; the younger segments have only one basal pore, but the older ones have 
two of them. The zooecia are much elongated, distinct, swollen; the frontal is 
covered with large, polygonal pores ; the peristomiale is not distinct from the frontal. 
The peristome is very salient, oblique, thin in the young zooecia, very thick in the 
old ones. The ascopore is large (0.02 mm.). The ovicelled zooecia have a larger 
external aperture. 
Old zooecia. Young zooecia. 
Measurements . — 
f Peristomice=0.16 mm. 
(Peristome=0.30 mm. 
=0.12 mm. 
= 0.18 mm. 
Zooecia 
7,3=1.40 mm. 
7.3=0.60-0.65 mm. 
= 1.40 mm. 
= 0.50-0.60 mm. 
