NORTH AMERICAN EARLY TERTIARY BRYOZOA. 
79 
Genotype. — Membranipora catenularia , Jameson, 1814. 
Range. — Cretaceous- Recent. 
The French author added that in creating the genus Pyripora in the Prodrome 
of Stratigraphic Paleontology he had placed there all species with colonies formed 
of isolated cells, but that now in the restriction of families it was necessary to 
give more special characters, and that therefore he would restrict Pyripora solely 
to species with large open cells without special pores. 
History and discussion . — In 1847, when D’Orbigny published his Prodrome, it 
was the author’s idea that this was only a provisional work which later researches 
would modify. D’Orbigny’s supplementary work classifying both fossil and 
recent bryozoa was jiublished in the Paleontologie Francaise of 1850 to 1852. This 
Fig. 20. — Genus Heterooecium Hincks, 1892. 
A, B. Heterooecium amplectens Hincks, 1892. 
A. Several zooecia, X 55. The small denti- 
cles are not only seen at the margin of the 
membranous area but are also visible through 
the calcified wall of the frontal surface. The 
acanthostegous ovicell (ov. a.) has its cavity 
between the spines and the ectocyst. B. The 
frontal wall of a zooecium, X 75, seen from the 
internal surface. (After Levinsen,1909.) 
Fig. 21. — Genus Pyripora D’Orbigny, 1852. 
A, B. Pyripora catenularia Jameson, 1814. A. Lin- 
ear form, X 25, with regenerated zooecia. B. Ex- 
pansion of zooecia, X 25, with all of them regen- 
erated. (After Hincks, 1880.) 
superseded the Prodrome, and of course is alone to be considered. In this special 
case, priority has no significance and can not be invoked for the date of a genus or 
species. 
Similarly, MacGillivray has given many definitions of his genus Iliantopora , 
and it becomes a question which one of them is to be recognized. Logically it 
should be the last one which is the result of the most detailed and complete studies 
of the author. 
In 1852 D’Orbigny cited four species of Pyripora — three fossil forms, Escha- 
rina crenulata Reuss, Escharina perforata Reuss, Griserpia pyriformis Michelin, 
and one recent, Pyripora ramosa D’Orbigny; but as he did not cite a type, the 
choice of one therefore becomes necessary. Common sense would indicate that his 
recent species, which has always been considered as synonymous with M embrani- 
