30 
which can be either convex, flat or coiicave. While the same is 
the case in the Eleidae, in the Ceidae on the contrary as in the 
genus Ceriopora there is no front wall visible on the surface of 
the colony, but very large hexagonal zooecial orifices, meeting in 
Sharp eclges. The most characteristic feature of the zooecium is, 
however, that the orifice begins with a funnel-shaped vestibular 
portion in the bottom of which is seated a much smaller round or 
oval opening, the entrance to the narrow, very thick-walled zooe¬ 
cial tube only dilating very little from beneath upwards. Each of 
the very thick partition-walls between two zooecial cavities does 
not end in a single plane but in two somewhat concave planes 
forming au angle with one another, and each zooecium being sur- 
rounded by six other zooecia, the funnel-shaped vestibulum is foiv 
med by the melting together of six concave planes sloping towards 
the zooecial entrance. The zooecial entrance is sometimes seated 
in the inferior part of the vestibulum, and in that case the ob¬ 
server at the first look will regard this as the superior part. A 
grinding away of the surface will not give an Eleid species the 
appearance characteristic to a Ceid. After such a grinding the 
colony will show a uumber of oval apertures separated by plane 
facets and not of funnel-shaped areas separated by sharp edges. If 
the superior part of the zooecial tube of an Eleid can be com- 
pared with a funnel, then the bottom of the funnel is seated a way 
down in the zooecial cavity, but in an Ceid the bottom of the fun¬ 
nel is identical with the entrance of the zooecial cavity. A similar 
funnel-shaped vestibulum has only been found in some palæozoic 
Bryozoa, f. i. in Rhombopora^), but liere the inner very thin- 
walled part of the zooecium strongly contrasts to the very thick- 
walled vestibular part. While no member of the Eleidae has been 
found still living I shall call attention to the interesting faet that 
the Ceidae which have hitherto been regarded as exstinet with the 
M E, O. Ulrich, Palæozoic Bryozoa, Geolog. Survey of Illinois, Vol VIII, 
Part. II, Section VI. 
