NORTH AMERICAN EARLY TERTIARY BRYOZOA. 147 



The recent species are : 



Callopora (Membranipora) Ihuata Linnaeus, 1758. 



Callopora (Membranipora) craticvla Alder, 1857. 



Callopora whiteavesii Norman. 1903. 



Callopora (Membranipora) nif/mnx Ilincks, 1882. 



Callopora (Membranipora) aurita Hincks. 1877. 



Callopora (Membranipora} Jwrrida Hincks, 1882. 



i \illopora (Membranipora) flu mi rill I Audouin, 1826. 



Callopora (Membranipora) californiemis Waters. 1898. 



Callopora (Membranipora) tenuirostrift Hincks. 1880. 



' 'allopora (Membranipora) curriroxtris: Hincks, 1861. 



CaUopora (Membranipora) alb/da Hincks, 1880. 



Callopora (Mcmbranipora) pinna Hincks. 1880. 



The fossil forms are: 



Callopora (Semiflustrina) monilifcra D'Orbigny, 1852. 



Callopora (Semiflustrina) inornota D'Orbigny, 1852. 



Callopora (Membranipora) ini-igilata'BrydoTie, 1910. 



Callopora (Membranipora) britannica Brydone, 1906. 



Callopora (Membranipora) woodwardi Brydone, 1906. 



Callopora (Membranipora) coralliformis Brydone, 1910. 



Callopora (Membranipora) calveti Cann, 1911. 



Callopora (Membranipora) nordgaardiana, Canu, 1911. 



Callopora (Pyriporella) amcghinoi Canu. 1911. 



Callopora (Membranipora) tuberosa Novak, 1877. 



Callopora (Bifiustra) solca Novak, 1877. 



Callopora (Membranipora) pcrisparsa Novak, 1877. 



Callopora (Membranipora) jerscyensis Ulrich and Bassler, 1907. 



Group of CALLOPORA LINEATA. 



CALLOPORA SEXSPINOSA. new species. 



Plate 3, fig. 16. 



Description. The zoaritim 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 hyperstominl, never 

 closed by the opercular valve, small, globular, salient. Sometimes there is a small 

 avicularium in the interzooecial angles. 



. |Ao=0.20 mm. . fZs=0.44-0.50 mm 



Measurements. Opesia /I-IOAI/I Zooecia 7 Ort 



1/0=0.12-0.14 mm. [fe=0.30 mm. 



Affinities. This species differs from ('allopora tuberosa in the absence of tuber- 

 osities on the mural rim and in the presence of six spines. 



It differs from Callopora craxxospina in the presence of ~ix widely spaced 

 spines instead of twelve. 



All of these species form part of the O , -nt<Vfi group of Canu. 



