ART. 21 CYCLOSTOMATOUS BRYOZOA — CANIT AND BASSLEB 13 



orbicular or elliptical. The peristomes are somewhat salient, thin, 

 scattered, arranged in quincunx. 



Measur ements. — Diameter of orifices, 0.14 mm.; diameter of peri- 

 stomes, 0.20 mm.; diameter of branches, 0.75 mm. 



Structure. — In transverse section the tubes are polygonal, equal, 

 with adjacent and very thick walls. In longitudinal sections the 

 tubes are cylindrical, with axial gemmation. The thickening of the 

 walls seems to correspond to the salient threads of the exterior sur- 

 face. The sectioned specimen was very small and did not permit of 

 better observations. 



This species differs from Clinopora striatopora Yine, 1885, from the 

 Albian of Cambridge, England, by its much smaller micrometric 

 measurements and very different arrangement of its salient threads. 



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

 ( rare) . 



Coty pes. —Cat. No. 69852, U.S.N.M. 



Family HETEROPORIDAE Pergens and Meunier, 1886 



Genus HETEROPORA Blainville, 1830 



HETEROPORA NUMMULARIA.new species 



Plate 20,, figs. 6-8 



Descriptioji. — The zoarium is free, discoid, little convex, unilamel- 

 lar, ornamented with feeble tuberosities. The apertures are orbic- 

 ular, arranged in quincunx, placed at the bottom of a small infundi- 

 buliform cavity. The mesopoves are small, irregular, polygonal, widely 

 spaced. 



Measurements. — Diameter of aperture, 0.08 mm.; diameter of 

 mesopores, 0.04 mm. 



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



Holotype.—Csii. No. 69853, U.S.N.M. 



Genus MULTICRESCIS D'Orbigny, 1852 



MULTICRESCIS TUBEROSA Roemer, 1839 



1909. Multicrescis tuberosa Gregory, Catalogue of the Cretaceous Bryozoa in the 

 British Museum, vol. 2, p. 205, figs. 52-54, pi. 9, fig. 4. (Bibliography 

 and geological distribution.) 



Our specimen corresponds exactly to Gregory's figure, so that a 

 new figure is unnecessary. Canu, in 1902, has noted the occurrence 

 of this species at Sainte-Croix. 



Occurrence. — Lower Cretaceous (Valangian) : Sainte-Croix (Vaud), 

 Switzerland. 



