ZOXATULA. 
211 
ZOJs'ATULID^. 
Stnonyms. 
Caveidce, pars, d’Orbigny, 1853. 
Frondiporidce, pars, Busk, 1859. 
Cerioporidce, pars, Hamm, 1881. 
Entalophoridce, pars, Pergens, 1890. 
Diagnosis. 
Trepostomata with dimorphic zooecia. The mesopores are 
abundant, and are restricted to special areas separating groups 
or bands of apertures. 
The zoarium is dendroid. 
Affinities. 
This family is most nearly allied to the Heteroporidse, from 
which it differs by the grouping of the apertures. 
The apertures may be in spiral bauds or rings as in Zonatula, 
in alternate groups or bands as in MuUhonopora, or in raised 
humps as in Plethopora and Sparsicytis. 
ZONATULA, Hamm, 1881. 
[Bry. mastr. Ob. -Sen. i., Cycl. p. 38.] 
Synonyms. 
Zonopora, pars, (['Oxhi^xiY, 1854; Vine, 1890-1. 
Plethopora, pars, von Hagenow, 1851. 
Heteropora, pars, Pergens, 1890 ; Vine, 1893. 
Ceriopora, pars, Pergens, 1894. 
Diagnosis. 
Zonatulidae with a dendroid zoarium of cylindrical stems, which 
are marked by spiral or annular constrictions. The zoarium 
is non-lamellar in structure. 
The mesopores are arranged in bands between the apertures 
of the zooecia. The bands of mesopores may be spiral or 
annular, and are depressed, giving rise to the spiral or zonal 
aspect of the stems. The walls of the zooecia appear 
moniliform in longitudinal sections. 
Apertures flush with the surface of the zoarium. 
Type Species. 
Plethopora pseudotorqmta^ von Hagenow, 1851. Senonian — 
Maastrichter Kalk : Maastricht. 
