BEYOZOAN FAUNA OF VINCENTOWN LIMESAND 61 



the pelma nor the pelmatidia, small ornaments that easily disappear 

 in fossilization. We have placed it in Anomithopora because of the 

 absence of avicularia and of the identity of the frontal with that of 

 Anomithopora implumis Lang, 1916, of the English Campanian. 

 Moreover, in its generic description (p. 165) the author does not give 

 a single positive character. 12 



The species differs from Anomithopora implumis Lang, 1916, in 

 its semicircular aperture, its larger dimensions, and in the presence 

 of two oral tuberosities. 



The same frontal structure is observable in the Recent Membrani- 

 porella nitida intermedia Norman, 1909 (Madeira), but the present 

 species differs in the absence of distal spines and of avicularia. It 

 differs finally from Lagynopora horsleyensis Lang, 1916, from the 

 English Senonian, very similar in aspect, in the presence of two 

 lacunae only (and not three), in its noncircular aperture, and in the 

 absence of a " median projection " on the apertural bar. 



The costules are very fragile and break so easily that there are few 

 complete zooecia on the zoaria. 



Occurrence. — Vincentown limesand : Rare at Vincentown, N.J. 



Holotype.—V.S.'NM. No. 73919. 



Genus HESPEROPORA Lang, 1916 



HESPEROPORA OCCIDENTALIS Lang, 1916 



Figure 1, B, C ; Plate 13, Figure 9 



1916. Hesperopora occidentalis Lang, Ann. Mag. Nat. Hist., ser. 8, vol. 18, p. 98. 



1922. Hesperopora occidentalis Lang, Catalogue of the Cretaceous Bryozoa in 



the British Museum, vol. 4, pt. 2, p. 171, text fig. 53a, b, pi. 3, fig. 12. 



Diagnosis. — Hesperopora with zooecia not much longer than wide ; 

 secondary aperture not well formed, and subcircular ; costae about 16. 



Description. — The zoarium is encrusting, unilamellar. The zooecia 

 are monomorphic. 



The adult zooecia, about 0.5 mm long and 0.35 mm wide, are wide 

 oval, the gymnocyst is of small extent but not hidden by interzooe- 

 cial secondary tissue ; the frontal is well arched, consisting of about 

 16 costae, each bearing 4 or 5 very small pelmatidia and having 

 about the same number of wide lateral costal fusions, leaving but 

 very small perforations (lacunae) between the costae; the costae 

 are firmly united in a median band of fusion; the apertural bar is 

 flattened in a distal-proximal direction and extended to form the 

 proximal shield of a secondary aperture ; the aperture is suboval or 



12 " Small Castanoporinao with comparatively few costae (20 or less), with no secondary 

 aperture and no or very few avicularia." A large number of very distinct species could 

 be classed under this definition. 



