68 
BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 
Calcified zooecia. — Calcification of the frontal in the Anasca and of the 
apertura in the Ascophora is a phenomenon quite frequent and still inexpli- 
cable. It is produced by the death of the polypide by accident or disease. Gen- 
erally the calcified lamella is perforated; rarely it remains entire; sometimes it 
disappears under the tremopores. 
We have mentioned the calcified zooecia each time that we have observed them, 
but for want of material we have not been able to make a detailed study. Follow- 
ing are some examples: 
Ramphonotus laevis, new species (pi. 1, fig. Id). 
Rectonychocella bilamellaria , new species (pi. 33, fig. 3). 
Floridinella vicksburgica Canu and Bassler, 1917 (pi. 82, fig. 26). 
M etroperiella biplanata , new species (pi. 47, fig. 15). 
M etroperiella porosa , new species (pi. 47, fig. 8). 
Smittina exig ca , new species (pi. 59, fig. 17). 
Smittina angidata Eeuss (pi. 60, fig. 8). 
Cyclicopora spongiopsis De Gregorio (pi. 88, fig. 10). 
Porella irregularis, new species (pi. 62, fig. 20). 
Rorella abdita , new species (pi. 65, fig. 3). 
Porella portentosa , new species (pi. 64, fig. 17). 
Adeonidae , Hippopodinidae. 
V estibular arch. — The superior portion of the tentacular sheath is called th& 
vestibulum. The latter is calcified sometimes in the vicinity of the anter of the 
apertura; this calcified lamella is the vestibular arch. It is very delicate and is 
little resistant in fossilization. We have rarely found it on our American speci- 
mens. (Figs. 15, C, D.) 
ZOARIUM. 
T erminology . — For a given species, the form of the zoarium is almost always 
identical; nevertheless it is not rare to find some species both incrusting and free, 
the latter form of growth being only an advanced phase of the former. Some of 
the genera of bryozoa, now entirely archaic, were based on growth forms alone, 
and their names we now preserve in the literature simpty in describing the form of 
zoaria. Among such names are the following: 
Eschara. refers to any free form of Ascophora with two lamellae back to back. 
Lunulites comprise all the free turbinate, conical forms. 
Lepralia is an incrusting form. 
Biflustra has reference to a free form of the Anasca with two lamellae back 
to back. 
Vincularia lias rod-like zoaria. . 
C elleporaria is a creeping form of the Anasca. 
Cellepora is any bryozoan made up of cumulate zooecia. 
1 1913. Larger (Ren§), La eontre-§volution ou degenerescence par 1’heiAditi? pathologique cause natu- 
relle de l’extinction des groupes animaux actuels et fossiles, Essai de palgopathologie generate comparer. 
Paris. 
