740 SYSTEMATIC PALEONTOLOGY 



Description. The small encrusting subcircular colonies of this species 

 with a maximum diameter of 4 mm. readily separates this form from all 

 other associated species. 



Occurrence. KANCOCAS FORMATION. Noxontown Millpond, Delaware. 



Collection. Maryland Geological Survey. 



Order CHI LOSTOM ATA 

 Family MEMBRANIPORIDAE 



Genus MEMBRANIPORA Rl.-iinville 



MEMBRANIPORA ANNULOIDEA Ulrich and Bassler 

 Plate XLVI, Fig. 3 



Membranipora annuloidea Ulrich and Bassler, 1907, Geol. Survey of New 

 Jersey, Pal., vol. iv, p. 335, pi. xxiii, fig. 16. 



Description. Zoarium encrusting. Zocecia from 0.5 mm. to- 0.65 mm. 

 in length, their width about three-fourths their length, more or less hex- 

 agonal in outline, sharply defined by depressed furrows. Zocecial aper- 

 tures about 0.2 mm. in length, subovate in outline, surrounded by a rather 

 broad, somewhat elevated, rounded marginal rim which is marked by a 

 series of from ten to thirteen small subcircular pits with raised borders. 

 Ovicells variable in their distribution, either abundant or much scattered, 

 usually a little broader than long with the side next the zooscial aperture 

 somewhat flattened, about 0.15 mm. in width. 



When worn, the marginal ring of pits about the zocecial apertures is 

 more or less obscure and sometimes wanting entirely. The species some- 

 what resembles the Italian Tertiary species M. annulus Manzoni, but 

 differs in having more rounded zocecia and more numerous pores. 



Occurrence. EANCOCAS FORMATION. Noxontown Millpond, Delaware. 



Collection. Maryland Geological Survey. 



Genus AMPHIBLESTRUM Gray 



AMPUIBLESTTIUM IIETEKOPORA (Gabb and Horn) 

 Plate XLVI, Figs. 5, 6 



Reptoflustrella f heteropora Gabb and Horn, 1862, Jour. Acad. Nat. Sci., 

 Phila. (2), vol. v, p. 162, pi. ii, flg. 50. 



