BEATRICEA-LIKE ORGANISM FROM THE MIDDLE ORDOVICIAN. 
5 
1, Plate III, and 1, Plate IV, in which the sections are not cut 
exactly perpendicular to the axis show wavy instead of straight 
lines, and a tangential section clearly shows the true nature of the 
structure (Plate III, figures 4,5). In the weathered specimens the 
outer shell is frequently preserved, and the filling of the tubes 
weathered away, so as to reproduce almost exactly the original 
structure. 
In only a single case have I found a specimen showing an 
end, and this specimen shows only one end (Plate I, figure 2). 
The specimen as now preserved is about 210 mm. long, and 
assuming that the natural position of the diaphragms is really 
convex upward, it shows the upper end of the specimen. The 
specimen enlarges into a sort of bulb at the top, both the inner 
tube and the outer sheath being enlarged. The specimen was 
originally weathered away about one-half at the lower end and 
apparently somewhat more than half at the bulbous end. Figure 
2, Plate I, shows the specimen as it was found. This specimen, 
like the others, shows the inner tube to be entirely distinct 
from the outer sheaths, and where the specimen is weathered, 
a zone 2 mm. wide has weathered away, so that there is a narrow 
and deep trench on each side of the inner tube. The whole 
diameter of the specimen at the smaller end is 23 mm. and the 
tube is 13 mm. in diameter at this point. At the widest part of 
the bulb the whole specimen is 35 mm. across, and the bulb 
of the tube itself is 21 mm. wide. The specimen seems, at the 
bulb, to be cut down below the median plane, so that these 
dimensions probably do not express the full size of the bulbous 
end. The outer sheath seems to consist of 4 or 5 thin layers 
and is most decidedly Stromatoporoid in appearance, even 
suggesting that it is an incrustation upon the inner tube. The 
sheath seems to have entirely enveloped the upper end, and sends 
out a curved portion of the sheath which extends some 20 mm. 
beyond the apex of the bulb. The presence of this sheath over 
the upper end of the organism effectually disposes of the idea 
that the animal could have been a coral. 
The condition of preservation of the inner tube of this 
specimen is of some interest in connexion with the question of 
the possible nature of the organism. In the untapering part 
