702 
BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 
Affinities . — This species differs from Filisparsa gracilis in the greater distance 
of the peristomes (more than 0.70 mm.) and in the presence of multiserial and 
claviform branches. The young branches are triserial. 
Occurrence. — Vic-ksburgian (Marianna limestone) : Murder Creek, east of 
Castlebury, Conecuh County, Alabama (rare) ; west bank Conecuh River, Escam- 
bia County. Alabama (rare). 
Vicksburgian (Red Bluff clay) : Seven and one-half miles southwest from 
Bladen Springs, Alabama (rare). 
Cotypes. — Cat. Nos. 65411, 65412, U.S.N.M. 
FILISPARSA B1SERIATA, new species. 
Plate 157, fig. 27. 
Description . — The zoarium is formed of thin, rectilinear, biserial branches. 
The tubes are little distinct, alternate, terminated by a short peristomie; the peris- 
tome is thin and orbicular. 
I Diameter of the peristome 0.10 mm. 
Measurements . — Distance between the peristomes 0.44 mm. 
[ Width of the branches 0.24 mm. 
Affinities . — This species greatly resembles Crisia , but the zoarium does not 
appear articulated. D'Orbigny called zoarial forms of this kind Unicrisia. The 
species differs from Filisparsa fallax, which is often biserial, in its smaller peris- 
tomial diameter (0.10 and not 0.16 mm.). 
Occurrence . — Vicksburgian (Marianna limestone) : West bank Conecuh River, 
Escambia County, Alabama (very rare). 
Holotype.— Cat. No. 65404, U.S.N.M. 
KEY TO THE DETERMINATION OF AMERICAN SPECIES OF THE ONCOUSOECIIDAE 
2 | Zoarium biserial .2. 
I Zoarium pluriserial 3. 
9 Peristome of 0.10 mm 
Peristome of 0.16 mm___ 
. Filisparsa biseriata. 
.Filisparsa fallax. 
3. 
4. 
5. 
6. 
Tubes arranged in alternate series, branches sinuous Filisparsa bint. 
Tubes arranged in transverse series 4. 
Tubes arranged in quincunx 5. 
Peristome of 0.20 mm Filisparsa typica. 
Peristome of 0.16 mm Filisparsa simulator. 
Peristome of 0.10 mm Filisparsa atomicula. 
Peristome of 0.20-0.24 mm., large branches Filisparsa ingens. 
Peristome of 0.24-0.28 mm Oncousoeeia varians. 
Peristome of 0.16 nun * 6. 
Branches always triserial 7. 
Branches pluriserial 8. 
7 | The peristomes are distant, 1.00 mm Filisparsa fallax. 
I The peristomes are distant from 0.60 to 0 80 mm Filisparsa gracilis. 
g | Lateral tubes turned toward the dorsal Oncousoeeia quinqueseriata. 
| Zoarium much compressed with claviform branches : Filisparsa laxata. 
