522 
BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 
Affinities . — The only specimen found has been figured. It is very pretty, 
but it has no ovicell. It much resembles Semi has w ell ia clara , but is distinguished 
from it in the place of the spiramen, which is much more distant from the peri- 
stomice. 
It differs from Tessaradoma grandipora in the much smaller diameter of the 
peristomice (0.09 and not 0.11 mm.) and in its thin peristome, measuring 0.10 
and not 0.15 mm. 
Fig. 154. — Genus Tessaradoma Norman, 1S6S. 
A-G. Tessaradoma gracile Sars, 1S50. A. Zoarium, natural size. B. Portion of zoarium, 
X 20. C. Zooecia, X 60. (After Hincks, 1SSO.) D. Schematic drawing of a longitudinal sec- 
tion through the zooecium. E. Drawing showing the introduction of the water by the spiramen 
in the peristomial tube just at the level of the operculum and above it. (B, I), E after Jullien, 
1903.) 
a, anter; c, compensatrix ; d, dorsal zooeeial wall; f, frontal zooecial wall; gt, tentacular 
sheath ; mr, retractor muscles of the polypide ; opf, closed operculum ; ogo, open operculum ; or, 
zooecial orifice or aperture; p, polypide; pe, peristome; pis, peristomice; go, poster; sp, spira- 
men ; spin, membraneous portion of the spiramen. 
O cevrrence. — Middle Jacksonian (Castle Hayne limestone) : Wilmington, 
North Carolina (very rare). 
Holotype. — Cat. No. 61170, U.S.N.M. 
TESSARADOMA GRANDIPORA, new species. 
Plate 67, figs. 2, 3. 
Description. — The zoarium is free, compressed, branched, formed of 3 longi- 
tudinal rows of zooecia ; the dorsal is a tremocyst with sulci bearing a median row 
