MULTIZONOPOKl, BIVESTIS, PLETHOPORA. 
227 
Affinities. 
As this genus includes Zonatulidee, in which the stems have 
the pores arranged in groups in oblique depressions, it is apparently 
a near ally of Zonatula. It differs from that genus by its bilaminar 
structure, and is therefore nearer to MuUhonopora, of which it 
may be a synonym. 
UXKEPRESENTED SPECIES, 
macropora, Hamm, 1881. 
Syx. Bivestis macropora, Hamm, 1881. Bry. mastr. Ob. -Sen. i., Cycl. p. 37. 
Char. — Zoarium of large, dichotomous, cylindrical branches. The larger 
apertures are somewhat triangular, with rounded angles. The smaller ones 
open in narrow, obliquely elongate areas, which are mostly slightly depressed. 
The smaller pores are a third to a fourth the diameter of the Idrger.^ 
Distrib. — Senonian — Maastrichtian ; Ciply, Folx-les-Caves, Belgium. 
PLETHOPORA, von Hagenow, 1851. 
[Bry. maastr. Kr. p. 45.] 
Synonyms. 
Pledopora, von Hagenow, 1850. 
Plethopora, d’Orbigny, 1854; Winkler, 1864; Ubaghs, 1879; Ulrich, 1900. 
Ceriopora, pars, Morren, 1829 ; von Hagenow, 1846 and 1851. 
Cory mhosa, pars, d’Orbigny, 1853. 
Fasciculipora, pars, Hamm, 1881. 
Sparsicytis, pars, Fillio/at, 1908. 
Diagnosis. 
Zonatulidae with a zoarium of short, thick stems, with the 
apertures collected into groups, which project in knobby 
elevations above the general level of the surface. The groups 
of apertures are separated by wide areas covered with 
mesopores. 
Type Species. 
Plethopora verrucosa, von Hagenow, 1851 : Bry. maastr. Kr. 
p. 45, pi. V. fig. 10. This species is especially mentioned by 
von Hagenow as the type. Maastrichter Kalk : Maastricht. 
^ Each large aperture is described by Hamm as surrounded by a circle of 
intermediate pores {Zwisehenporeri) . Whether these are the same as the smaller 
Zelldffnungen is not clear. 
