ART. 2] CYCLOSTOMATOUS BRYOZOA CANU AND BASSLER 33 



NEUROPORA MICROPORA, new species 



Plate 25, figs. 4-8; Plate 30, fig. 20 



Description. — The zoariuni is free, hemispherical or pyriform; the 

 base is always narrower. The orifices are very small, polygonal, 

 irregular, surrounded by short points. The veinules are rare and 

 irregular. 



Measurements. — Diameter of orifice, 0.08 mm.; length of large 

 zoaria, 20 mm. 



Structure. — This species is very well characterized by the smal 

 diameter of its orifices. 



The longitudinal section is quite identical with that of the geno- 

 type admirably figured by Hennig in 1893. It is quite complicated 

 by the very large number of diaphragms. A certain number of the 

 latter are simultaneous and form a kind of zonal line. The walls 

 are thick and formed by a very finely vesicular tissue. Gemmation 

 is peripheral. 



In tangential sections the tubes are polygonal, not adjacent, sepa- 

 rated by a vesicular tissue. A second orbicular tube is placed in 

 their interior. 



Occurrence. — Lower Cretaceous (Aptian) : Faringdon, England. 



Cotypes.—C&t. No. 69877, U.S.N.M. 



NEUROPORA TENUINERVOSA, new species 



Plate 25, figs. 16-19 



Description. — The zoarium is free, cylindrical, branched, borne on 

 a base of less diameter. The orifices are small, polygonal, arranged 

 in quincunx, separated by little salient tuberosities. The centers of 

 convergence of the veinules are large smooth, salient tuberosities. 

 The veinules are numerous, very narrow, often little visible, arranged 

 in radiating lines around the zoarial tuberosities. 



Measurements. — Diameter of orifices, 0.06-0.08 mm.; diameter of 

 zoarium, 5 mm. 



Affinities. — Neuropora tenuinervosa differs from N. micropora in its 

 branched zoarium and in the presence of salient centers of convergence. 

 It diffeis from Neuropora arhuscula in its smaller orifices, in its less 

 salient visors, and in the presence of salient centers of convergence 

 of the veinules. 



The veinules are very narrow, quite transitory, as they disappear 

 upon weathering, so that certain specimens lack them entirely, thus 

 exhibiting the aspect of Spinopora. 



Occurrence. — Lower Cretaceous (Aptian): Faringdon, England 

 (rare) . 



Coty pes. —C&t. No. 69878, U.S.N.M. 

 53648—26 3 



