178 
BULLETIN 125, UNITED STATES NATIONAL MUSEUM. 
imal border being very concave. There are two oral spines and a small oral very- 
inconstant avicularium. On the deep zooecia the apertura only is visible. 
Measurements .—Apertura 
ha = 0.15 mm. 
la =0.15 mm. 
Affinities .—This species differs from Holoporella massalis Ulrich and Bassler, 
1904, in the absence of areolar pores. In the presence of two oral spines it approaches 
Holoporella hicornis, but differs from it in its larger micrometric dimensions and 
in the absence of areolar pores. It is also quite close to Cellepora tuberosa Smitt, 
1872, in the presence of a small oral avicularium and in the nature of the frontal; 
it differs from it in the presence of two spines and in a very different zoarial form. 
Only the figured specimen has been found. More plentiful material will later 
on permit a more exact study. 
The absence of areolar pores may cause our generic determination to be 
doubted; but they are easily obliterated on the fossils. 
Occurrence .—Miocene (Yorktown formation): Yorktown, Virginia (very rare). 
Holotype. —Cat. No. 68705, U.S.N.M. 
HOLOPORELLA BICORNIS, new species. 
Plate 32, figs. 1-4. 
Description .—The zoarium is formed of large shapeless masses attached to 
algae. The zooecia are erect, salient, very convex; the frontal is smooth, surrounc^d 
by some much-scattered areolar pores. The apertura is semilunar with a concave 
proximal border; the peristome is wide and bears two large spines. A small, salient 
avicularium terminates the median umbo. The deep zooecia have only their 
apertura visible. The interzooecial avicularia are rare and elliptical. Sometimes 
there is a vibraculum on the zooecia. 
,, . . f7tu = 0.13 mm. 
Measurements .—Apertura 7 - „ 
[la =0.12-0.15 mm. 
Affinities .—Above many of the apertures a little pore in the form of a lunar 
crescent is visible; it has the aspect of vibraculum; it is placed on the distal zooecium 
or indeed it is interzooecial. Its function is unknown. 
This species resembles Reptocelleporaria similis Tuomey and Holmes, but the 
figure of these authors indicates a greater number of areolar pores. It differs 
from Holoporella albirostris Smitt, 1872, in the presence of two large oral spines and 
in the massive form of the zoarium. In each zoarium there is always a perforation 
which is the trace of the alga to which the zoarium was attached. This, moreover, 
is the most frequent habitat of the Celleporidae. 
Occurrence .—Pliocene (Waccamaw marl): Waccamaw River, Horry Countv. 
South Carolina (rare). 
Cotypes. —Cat. No. 68706, U.S.N.M. 
HOLOPORELLA UMBONATA, new species. 
Plate 40, figs. 8, 9. 
Description .—The zoarium incrusts shells, bryozoa or algae. The zooecia are 
oriented, distinct, elongate, separated by a deep furrow; the frontal is convex, 
smooth, surrounded by pores and areolar costules; a large umbo terminated bv an 
