90 BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 
case of doubt the conscientious naturalist should remain silent or should figure the 
specimens. 
The lucid spots are rather irregular on the recent specimens. Canon Norman 
was unable to see them, but Osburn has figured them. We have not observed them 
in all cases. On the fossils the corresponding distal impressions are very incon- 
stant. They are visible on certain specimens and have disappeared entirely on 
others. The granulations of the mural rim are very inconstant, and we have 
observed but a single case of total regeneration. 
This species differs from C onopeum wilcoxianicum in the thinness of its mural 
rim, from 0 . hoockeri in the absence of the hump-like gymnocyst, and from 0 . con- 
cavum in the absence of the proximal concave crvptocyst. Its zooecia do not 
excavate the host like the two latter forms. 
Occurrence. — Claibornian (Lisbon formation) : Wautubbee Hills, 4 miles south 
of Enterprise, Clarke County, Mississippi. 
Lower Jacksonian (Moodys marl) : Jackson, Mississippi. 
Middle Jacksonian: Eutaw Springs, South Carolina. 
Geological distribution. — Lutetian, Auversian, and Stampian of the environs of 
Paris (Canu) ; Miocene of Tunis (Canu) ; Burdigalian of Garcl and of Herault in 
France (Canu) ; Helvetian of Italy (Miclielin, Seguenza), of Gard, of Herault, and 
of Touraine in France (Canu) ; Tortonian of Austria-Hungary (Reuss) ; Plaisan- 
cian of England (Hincks) ; Quaternary of England (Bell) and of Argentina 
( Canu ) . 
Habitat. — The habitat of this species is still very obscure on account of the 
difficulty of its determination. It certainly exists in the North Atlantic off the 
coasts of France, England, Canada, and the United States and in the Pacific off 
Alaska and California. It has not yet been observed with certainty in the Mediter- 
ranean and in the tropical zone. Bifustra lacroixii Smitt found off Florida appears 
to be a different species, and Osburn, who has rediscovered Smitt’s species, also 
doubts its identity. 
Conopeum lacroixii does not appear to inhabit the great depths, but it is 
common near the shores. 
Plesiotype. — Cat. No. 63845, U.S.N.M. 
CONOPEUM TUBEROSUM, new species. 
Plate 19, figs. 6, 7. 
Description . — The zoarium incrusts oysters. The ancestrular zooecia are 
isolated. The zooecia are elongated, distinct, elliptical, or pyriform; the gymnocyst 
is inconstant, small, convex, bearing very often a small tuberosity / the mural rim 
is wide, flat, finely striated, with an acute termen, a little enlarged at the base. The 
opesium is large, elliptical, very finely crenulated. The interopesial cavities are 
irregular, inconstant, triangular, or lozenge-shaped. 
„ \ho— 0.22-0.26 mm 
Measurements . — Opesium , n + 
?o=0.1U0.16 mm. 
Zooecium 
\Lz-=- 0.40 mm. 
\lz— 0.28-0.30 mm. 
