MOLLUSCOIDEA. 343 



1896. Membraniporella Abbotti Ulrich, Zittel-Eastman Text 



Book of Pal., p. 287, fig. 479. 



1905. Escharipora abbottii Johns., Proc. Acad. Nat. Sci. Phil., 

 1905, P- 5- 



Description. Zoarium encrusting or growing- in bifoliate 

 plates. Zooecia elongate-subelliptical or subhexagonal in outline, 

 usually arranged in more or less regular longitudinal series and 

 in quincunx, about 0.5 mm. in length, the length about twice the 

 width. Zocecial apertures subcircular or subquadrate with 

 rounded angles, sometimes rounded in front and truncate pos- 

 teriorly; they are situated anteriorly and occupy about one-third 

 of the length of the zocecium ; back of the aperture the surface is 

 covered by a thin, flat or slightly convex wall slightly depressed 

 below the zocecial margin, which is marked by about 14 or 

 15 lateral grooves radiately arranged posteriorly, leaving a nar- 

 row, smooth area along the median line, these grooves are 

 either slit-like openings through the wall or they are pierced by 

 lines of pores, it cannot be determined which from the specimens 

 observed. Avicularia usually two to each zocecium, subovate in 

 outline and situated one on each side of the zocecial aperture, from 

 the lateral margins of which they are directed obliquely outward 

 and backward. Ovicells present or absent, subglobular in form, 

 situated just in front of the zocecial apertures. 



Remarks. Gabb and Horn apparently gave two names to this 

 species, Escharipora Abbottii to those forms in which the ovi- 

 cells are wanting, and Reptescharipora marginata to those in 

 which the ovicells are present. Both conditions are apparently 

 present in one and the same species. The species resembles 

 Cribrilina modesta Ulrich, 1 from the Eocene of Maryland, and 

 if the grooves upon the outer walls of the zocecia should be found 

 to be furnished with lines of pores in their bottoms, and not to 

 be open slits, the species should doubtless be referred to the genus 

 Cribrilina rather than Membraniporella. 



Formation and locality. Vincentown limesand, Vincentown 

 (154), near M|ullica Hill (Gabb and Horn). 



Geographic distribution. New Jersey. 



Md. Geol. Surv., Eocene, p. 218, pi. 60, Figs. 12-13. 



