372 
PETALOPOKIDiE. 
Type Species. 
Phormopora irregularis, 1887. Seuonian: Riigcn. 
irregularis, Marsson, 1887. 
Syn. Fliormopora irregularis, Marsson, 1887. Bry. Riig. : Pal. Abh. vol. iv.. 
p. 33, pi. iii. fig. 4. 
Char. — Zoarium of thin stems : the apertures occur in irregular series. Apertures- 
small. Pores of the tubuli on the reverse surface scattered between faint 
longitudinal furrows. In transverse section the zooecia of the axial bundle 
occupy nearly the whole section. 
Distrib. — Senonian — Campanian ; Biigen. 
Family PETALOPOPJD^. 
Synonyms. 
Caveidcc, pars, d’Orbigny, 1854. 
Cerioporidea, pars, Novak, 1877. 
Entaloplioridce, pars, Marsson, 1887 ; Pergens, 1890. 
Diagnosis. 
Cyclostomata Cancellata in which the zoarium is erect and 
dendi’oid ; the zooecia open on all sides of the branches. The 
walls are perforated by numerons maculae. 
Affinities. 
This family in the Cancellata corresponds to the Entalophoridae 
among the Tuhulata. The zoarial characters of the two families 
are the same, hut the walls of the zooecia in the Petaloporidae are 
perforated by numerous maculae, which usually appear on the 
surface as pores, though they may he externally concealed by 
epitheca. 
The main problem in connection with this family is the structure 
of the maculae. In the typical genus Petalopora (syn. Cavea) 
the maculae superficially resemble the small pores of Heteropora. 
Accordingly M. Pergens has included Cavea in Seteropora. But 
the structure of the small pores in Petalopora and Seteropora 
is essentially distinct. The former are mural cavities, which are 
not continued into the axial bundle of zooecia. In Heteropora, 
on the contrary, the smaller pores are rudimentaiy zooecia, and are 
