478 
BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 
frontal and placed in all directions there is a very large avicularium with small 
opesium and of which the mandible is rounded like the beak of a duck. 
M easurem ents. — Zooec-i a 
| Zs=0.35 mm. 
1 Is =0.25 mm. 
Affinities. — The European type has distinct and marginated zooecia; the large 
frontal avicularium appears to us as placed nearer the apertura. These insignifi- 
cant, differences do not permit us to make a distinct species out of our American 
specimens. 
The presence of the large frontal avicularium differentiates clearly this species 
from Rhampkostomella simplex and Rhampkostomella convexa. 
Occurrence. — Middle Jacksonian: Wilmington, North Carolina (rare) ; Eutaw 
Springs, South Carolina (very rare). 
Geological distribution. — -Priabonian of the Vicentin (Waters). 
H olotype. — Cat. No. 64140, U.S.N.M. 
RHAMPHOSTOMELLA CONVEXA. new species. 
Plate 62, fig. 12. 
Description. — The zoarium incrusts bryozoa. The zooecia are distinct, ellip- 
tical. a little elongated, separated by a furrow; the frontal is very convex and is 
formed of a pleurocyst very finely and very irregularly granulated. The peristome 
is little salient and beat's two symmetrical spines; the peristomice bears an asym- 
metrical sinus formed bv a quite salient oral avicularium with pivot and opening 
exteriorly ; the aperture is oblique, imbedded, hidden by the oral avicularium. The 
ovicell is small, salient, placed on the distal zooecium; it is very widely open above 
the apertura and faces the avicularium. 
M easurenents. — Zooecia 
fZs= 0.35-0.45 mm. 
1 fe= 0.25-0.30 mm. 
Affinities. — In this species it is absolutely impossible that the operculum could 
close the ovicell; it is closed by the ectocyst itself or by a special membrane. We 
can only form an hypothesis, for we are totally^ ignorant of the larval system of 
the Smittinidae in general. 
This species differs from Rhampkostomella simplex in its zooecia distinct and 
convex, and in its oral avicularium, which opens exteriorly and not in the peri- 
stomie. 
It differs from Rlxamphostomella brendolensis Waters, 1891. in the absence of 
the large frontal avicularium. 
Occurrence. — Middle Jacksonian: Rich Hill, Crawford County, Georgia 
(rare) ; near Lenucls Ferry, South Carolina (rare). 
Upper Jacksonian (Ocala limestone) : Old Factory, 14 miles above Bain- 
bridge, Georgia (rare). 
H olotype. — Cat. No. 64141, U.S.N.M. 
