70 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 67 



The exterior lamellae could become elevated to form false 

 ramifications. 



The longitudinal section shows a number of tubes cut tangentially 

 and appearing in gray or in black. The facettes were in reality 

 arranged regularly in transverse rows. 



In Ceriocava the longitudinal section has different aspects accord- 

 ing as the facettes are arranged in quincunx or transversely. This 

 obsvervation was known, but it is important that it has been con- 

 firmed on the same species. 



The central tubes grow by axial gemmation around a single tube 

 which branches only at the bifurcations of the branches. This tube 

 appears in transversal sections with a larger diameter. 



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

 Switzerland (common). 



Cotypes.—Csit. No. 69922, U.S.N.M. 



CERIOCAVA INGENS, new species 



Plate 8, figs. 8-12 



Descripiion. — The zoarium is free, large, arboiescent; the branches 

 are compressed or cylindrical. The facettes are distinct, separated 

 by a furrow of little depth, somewhat convex, smooth, arranged 

 in quincunx, pierced at the middle by the aperture. The aper- 

 ture is orbicular and surrounded by a thin, little salient peristome. 

 The orifices of the tubes without facettes are large and irregularly 

 polygonal. 



Measurements. — Diameter of aperture, 0.14 mm.; diameter of 

 peristome, 0.17 mm.; diameter of facettes, 0.30-0.40 mm.; diameter 

 of orifices without facettes, 0.20 mm.; diameter of zoarium, 10 mm. 



Affinities. — As in all species of the genus, the orifice of the tubes 

 without facettes is expanded; it measures internally at the base of 

 the visible peristomie 0.17 mm., but externally its diameter is about 

 0.40 mm., exactly equal to that of the tubes with facettes. 



The species difl:eis from Dijdocava inordinata in its monomorphic 

 zooecia, its large zoarium, and its much larger micrometric measure- 

 ments. On the figured specimen the tubes with facettes are at the 

 bottom of the zoarium; the branches are deprived of them. 



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

 Switzerland (very rare) . 



Cotype.—C&t. No. 69923, U.S.N.M. 



CERIOCAVA TENUIRAMA, new species 



Plate 10, figs. 1-4 



Description. — The zoarium is free, cylindrical, bifurcated, formed 

 of small branches. The orifices of the tubes without facettes are 

 lozenge-shaped, elongated, arranged in transverse rows. The orifices 



