NORTH AMERICAN EARLY TERTIARY BRYOZOA. 
147 
The recent species are : 
Callopora (M embranipora) lineata Linnaeus, 1758. 
Callopora (M embranipora) craticula Alder, 1857. 
Callopora whiteavesii Norman. 1903. 
Callopora, (Membra, nip ora) nigrans Ilincks, 1882. 
Callopora (M embranipora) aurita Hincks. 1877. 
Callopora (M embranipora) horrida Hincks, 1882. 
Callopora (M embranipora) dumerilli Audouin, 1826. 
Callopora (M embranipora) calif orniensis Waters. 1898. 
Callopora (M embranipora) tenuirostris Hincks, 1880. 
Callopora (M embranipora) curvirostris Hincks, 1861. 
Callopora (M embranipora) albida Hincks, 1880. 
Callopora (M embranipora) plana Hincks, 1880. 
The fossil forms are : 
Callopora ( Semiflustrina ) monilifera D’Orbigny, 1852. 
Callopora (Semiflustrina) inornata D’Orbigny, 1852. 
Callopora (M embranipora) invigilata Brydone, 1910. 
Callopora (M embranipora) britannica Brydone, 1906. 
Callopora (M embranipora) woodwardi Brydone, 1906. 
Callopora (M embranipora) coralliformis Brydone, 1910. 
Callopora (M embranipora) calveti Canu, 1911. 
Callopora (M embranipora) nordgaardiana , Canu, 1911. 
Callopora ( Pyriporella ) ameghinoi Canu, 1911. 
Callopora (M embranipora) tuberose, Novak, 1877. 
Callopora ( Biflustra ) solea Novak, 1877. 
Callopora (M embranipora) perisparsa Novak, 1877. 
Callopora (M embranipora) jerseyensis Ulrich and Bassler, 1907. 
Group of CALLOPORA LINEATA. 
CALLOPORA SEXSPINOSA, new species. 
Plate 3, fig. 16. 
D esc-ription .- — The zoarium incrusts shells. The zooecia are distinct, separated 
by a deep furrow, elongated, oval, the point above; the mural rim is salient, 
rounded, ornamented by six large spines, somewhat wider in its proximal part. 
The opesium is regular, elliptical or oval. The ovicell is hyperstomial, never 
closed by the opercular valve, small, globular, salient. Sometimes there is a small 
avicularium in the interzooecial angles. 
Measurements . — Opesia 
ho= 0.20 mm. 
lo= 0.12—0.14 mm. 
Zooecia 
f ZA=0.44-0.50 mm. 
\lz=0 . 30 mm. 
Affinities .— This species differs from Callopora tuberosa in the absence of tuber- 
osities on the mural rim and in the presence of six spines. 
It differs from Callopora crassospina in the presence of six widely spaced 
spines instead of twelve. 
All of these species form part of the Ornatella group of Canu. 
