BKYOZOAN FAUNA OF VINCENTOWN LIMESAND 17 



(setiform) distal avicularium * * * for which we might pro- 

 pose a special genus, clearly equatorial * * *." 



The type of the genus Ellisina is Memhranipora levata Hincks, 

 1882, 6 in which the ovicell is hyperstomial and closed by the oper- 

 culum. The coronata group is not then the levata group in spite of 

 exterior appearances. 



Affinities. — Cranosina differs from Ellisina Norman, 1903, in the 

 presence of an endozooecial ovicell. It differs from Setosellina Cal- 

 vet, 1907, in the occurrence of a distal, transverse avicularium and 

 not a longitudinal vibraculum. In the list of Cretaceous Ellisina 

 given by Voigt, 1930, all three genera appear to be represented. 



CRANOSINA ALTIMURALIS Ulrich and Basgler, 1907 



Plate 2, Figures 7, 8 



1907. Escliariiiclla altimuralis Ulrich and Bassler, in Weller, Geol. Surv. 

 New Jersey, Paleontology, vol. 4, p. 339, pi. 24, figs. 9, 10. 



Description. — The zoarium encrusts the debris of shells and Bry- 

 ozoa; the dorsal is a very thin pellicle incompletely covering the 

 substratum. The zooecia are adjacent, not separated, subrhomboidal 

 in outline with very thin walls ; the opesium is of the same form as 

 the zooecium. There are four pairs of small septulae widely opened. 

 The ovicell is endozooecial, small, and convex and covers the two 

 distal septulae. Each zooecium is surmounted by a small triangular 

 avicularium, oblique, oriented a little upward, symmetrical, with two 

 denticles for pivot; its surface, oriented toward the proximal zooe- 

 cium, is oblique to the plane of the latter; the beak is pointed and 

 very salient. 



Me asivrements . — 



_ . ( Zs = 0.5-0.63 mm. | nA ni . . . 



Zooecium \ , _ „ n ... 20 or 21 zooecia in 4 sq. mm. 



| Iz = 0.36-0.41 mm. J n 



Variations. — The micrometric variations are very great, for on the 

 same colony the zooecia range from 0.5 to 0.75 mm in length and 

 from 0.25 to 0.5 mm in width. The irregularities of the substratum 

 often give to the cells a most fantastic aspect. 



Occasionally the ovicell is surmounted by an avicularium, which 

 covers it with a secondary calcification. 



We have observed the phenomenon of a double ancestrula, but we 

 have not seen regenerated zooecia. 



Occurrence. — Vincentown limesand : Very common at Vincen- 

 town, N.J., but rare at Noxontown Millpond and near Odessa, Del. 



Holotype and plesioti/pe.— U.S.N. M. Nos. 52594, 73866. 



8 Miss Hastings, in 1930, published a good study of Ellisina levata: Cheilostomatous 

 Polyzoa from the vicinity of the Panama Canal. Proc. Zool. Soc. London, 1929, p. 713, 

 pi. 8, figs. 36, 37. 



