396 Systematic Paleontology 



" The phragmocone is seldom seen showing the lines of septa, and when 

 seen they appear to be only external or marginal. Among the few bearing 

 the lines which I have examined none have shown the septa extending 

 across. This body is rather abruptly obconical, and is just a little ovate in 

 transverse section, one side being a very little angular and with a raised, 

 rounded longitudinal ridge, corresponding to the angularity of the solid 

 fissure of the guard being regularly curved, as is the inside of the cavity 

 itself. The lines of septa are very numerous and closely arranged near 

 the pointed end, but gradually and regularly increase in distance from 

 each other, so that where the diameter of the cone reaches five-eights of an 

 inch, the septse are fully a twelfth of an inch apart. In their direction 

 across the cone they are nearly straight, except on the angularity, where 

 they are slightly advanced. The position of the siphuncle I have not 

 observed. 



" The substance of the guard is quite dense, and is transversely fibrous, 

 the fibers being very slightly directed downward from the initial line, 

 which is never quite central but is usually placed considerably nearest to 

 the fissured margin of the guard." — Whitfield, 1892. 



Type Locality. — Arneytown, ISTew Jersey. 



Belemnitella americana is known in Maryland only from Bohemia 

 Creek, Cecil County. It is perhaps the most valuable horizon marker of 

 the Cretaceous, since it has never been reported' from either above or 

 below the Monmouth and is determinable from the merest fragment. 



Occurrence. — Monmouth Formation. Briar Point, Chesapeake and 

 Delaware Canal, Delaware ; ] mile south of Bohemia Mills, head of 

 Bohemia Creek, Bohemia Mills, 1 mile southwest of Bohemia Mills, Cecil 

 County, Maryland. 



Collections. — Maryland Geological Survey, Philadelphia Academy of 

 Natural Sciences. 



Outside Distribution. — Monmouth Formation. Navesink marl, New 

 Jersey. Peed.ee Sand. North and South Carolina. Selma. Exogyra cos- 

 tata zone, east-central Mississippi, Lee and Tippah counties, Mississippi : 

 Wilcox and Sumter counties, Warrior and Tombigbee rivers, Alabama. 

 Senonian. Europe, Aff. Belemnitella mucronata. 



