MOLLUSCOIDEA. 355 



a more or less obscure resemblance to the figure W. Behind the 

 lip the surface slopes rapidly, and in the most nearly perfect ex- 

 ample is granulose. In the depressed space in front of the aper- 

 ture there are, normally, three small raised avicularia ( ? 

 vibracula), while a few larger avicularia, differing further from 

 the others in being divided into two unequal parts by a cross- 

 bar, are scattered without order among the zooecia. Ooecia are 

 not often seen. When present they occupy the depressed space 

 in front of the aperture, are cucullate, about as large as the 

 zooecial aperture and usually bear a furrow running from the 

 summit to- the concave edge." (Ulrich. ) 



Remarks. — This species approaches nearer to M. typica than 

 to any other, but the zoarium in the twO' forms is very different, 

 this one being incrusting, while the other rises in erect bifoliate 

 branches. The surface characters of the zooecia are also suf- 

 ficiently distinct to make the two species easily distinguishable. 

 Besides its occurrence in the Cretaceous Vincentown beds of 

 New Jersey, the species also occurs, and, indeed, was originally 

 ■described from the Eocene of Maryland. 



Formation and locality. — -Vincentown limesand, Vincentown 



<I54)- 



Geo'grapliAC distribution.. — New Jersey ; Eocene of Maryland. 



Mucronella pumila (Gabb & Horn). 

 Plate XXVI., Fig. 16-17. 



1862. Cellepora pumila G. & H., Jour. Acad. Nat. Sci. Phil., 



2d ser., vol. 5, p. 126, pi. 19, fig. 8. 

 1864. Cellepora pumila Meek, Check List Inv. Eoss. N. A., 



Cret. and Jur., p. 3. 

 1868. Cellepora pumila Con., Cook's Geol. N. J., p. 722. 

 1905. Cellepora pumila Johns., Proc. Acad. Nat. Sci. Phil, 



1905, P- 5- 



Description. — Zoarium encrusting. Zooecia minute, arranged 

 in regular lines longitudinally, but rarely in regular quincunx, 

 subovate in outline, convex, bounded by depressed lines formed 

 hy the meeting of the convex surfaces. Zooecial apertures, very 



