92 
BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 
The zooecia are very fragile ; when they have disappeared, an elliptical cavity 
is left on the substratum, as if the latter had been eroded. Conopeum concavum 
also possesses this peculiarity ; but even when occurring together on the same shell, 
the two species can not be confounded, since the latter is provided with a concave 
crvptocyst and has no elevated gymnocyst. 
Again, this species differs from C onopeum wilcoxianicum, in the thinness of its 
mural rim, and from C. lacroixii in the rare occurrence of its interopesial cavities. 
Occurrence . — Lower Jacksonian (Mooclys marl): Jackson, Mississippi (rare). 
Geological distribution . — Nummulitic limestone of India (Haime) ; Priabonian 
of Vicentin (Reuss, Waters). 
Plesiotype. — Cat. No. 63869, IJ. S. N. M. 
CONOPEUM CONCAVUM, new species. 
Plate 19. figs. 11-1?,. 
Description . — The zoarium consists of large colonies inerusting shells. The 
zooecia are distinct, elongated, elliptical; the mural rim is very thin, but it is much 
enlarged proximally, forming a true cryptocyst, always concave. The opesium is 
regular and elliptical. The interopesial cavities are large, triangular; they often 
join each other and become confluent. The dorsal which excavates in the sub- 
stratum, bears two impressions and two distal septulae. 
„ f^o=0.28-0.32 mm. 
Measurements.- Opesia^ al8 _ 0 . 20 mm . 
Affinities . — Like Conopeum, hoockeri this species appears to excavate a place 
for itself in the substratum, but it presents furthermore some remarkable peculi- 
arities. The opesium of certain zooecia is closed by a perforated lamina. In the 
articulated species, such zooecia correspond to the radicular pores, but here we are 
totally ignorant of their function. On other zooecia there is a genuine cryptocyst 
and an aperture closed by a calcified operculum. I inally, total regeneration mani- 
fests itself by a secondary mural rim within the opesium. 
This species differs from C onopeum wilcoxianicum , in its thin mural rim, 
from C . hoockeri in its concave crvptocyst and its interopesial cavities, and from 
C . lacroixi in its concave cryptocyst. 
Occurrence . — Lower Jacksonian (Mooclys marl) : Jackson, Mississippi (rare). 
Vicksburgian (Byram marl) : Vicksburg, Mississippi (rare). 
Cotypes. — Cat. No. 63870, U.S.N.M. 
CONOPEUM LAMELLOSUM, new species. 
Plate 20, figs. 1-9. 
Description . — The .zoaria are large undulating fronds formed of multiple 
lamellae growing back to back. The zooecia are distinct, somewhat elongate, 
elliptical; the mural rim is flat, finely punctate, projecting distally, and enlarged at 
the base into a small cryptocyst. The opesium is regular, elliptical, entire or very 
