276 PALEONTOLOGY OF NEW JERSEY. 



but it is difficult to determine liow far this feature may be reliable. Many 

 of them are decidedly ovate, others so slightly so as to make the feature 

 difficult of detection, while by far the most of the examples which I have 

 seen would be called oval by anyone not expecting to question the form. 



The septa are closely arranged in some and in others somewhat distant, 

 while they are not infrequently quite irregular in distance in the same indi- 

 vidual, and sometimes do not extend the entire distance across the tube, but 

 interfere with and terminate against the one below, so as to count irregular 

 on opposite edges of the tube. In one specimen which comes to me from 

 the Acad. Nat. Sci., Phila. this occurs twice within a length of an inch and 

 a half, and all the septa in that distance are quite crowded. The septa 

 have three lobes on each side of the tube and a small one on the ventral 

 edge; while the siphonal lobe is simply bifid and the branches very small 

 and short. The first dorsal lobe is much smaller than the others and 

 directed somewhat inward toward the side or away from the dorsal edge. 

 The second lobe is much larger and more numerously branched, while the 

 third is still larger than the second as well as more complicated in structure 

 and the ventral lobe quite small, short, and simple, but numerously digitate 

 according to the size and age of the specimen. In detail the lobes and 

 sinuses vary with size and age, but are almost as variable as the specimens 

 are numerous, but in all the specimens which I have examined the second 

 lobe is usually bilateral, nearly symmetrically so, and the sinuses in the 

 lower half of the lobes are broad and rounded without serratures on their 

 margins. 



Siphon situated just within the narrow edge of the tube and of rather 

 large size. 



Shell marked on the outer portions in specimen of large size by undu- 

 lations of growth indicating the outline of the aperture, and showing a 

 considerable extension upward of the shell on both edges and a corre- 

 sponding broad sinus on the sides, the extension on the siphonal side being 

 much the longest. 



Formation and localities: In the Lower Green Marls throughout then- 

 extension in New Jersey and Delaware. Most common in Burlington 

 County, New Jersey. MuUica Hill has also furnished many. The bluffs 

 at Neversink, New Jersey, and Monmouth County have yielded some. 



