282 PALEONTOLOGY OF NEW JERSEY. 
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. 
It is almost useless to institute comparisons between this and other 
species except the B. mucronatus of Schlotheim; while it is equally difficult 
to point out reliable differences between that and the New Jersey form. 
There is, however, one marked difference between them, so far as I have 
been able to examine European specimens of B. mucronatus, and there are 
many, both English and German. This is the relative length of the guard 
below the base of the slit or fissure, which in the American examples is 
proportionally longer than in the European, varying from half an inch to 
over an inch in different examples. This feature of course is a variable 
one, and perhaps may not be considered as of importance or reliable, yet 
it nevertheless exists; but in other points they agree very closely. Still I 
am inclined to hold to Dr. Morton’s name for our American specimens, 
although forms like this, which may have béen to some extent pelagic, are 
more apt to be inhabitants of widely separated continents than littoral 
species of molluscs are. 
Formation and localities: I think this: species is, so far as yet known, 
confined to the Lower Marl Beds. It is found at most of the outcrops of 
that bed throughout the State, and is abundant at many. Marlboro, Free- 
hold, Creamridge, Mullica Hill, and many other localities furnished them 
in great profusion, most of the examples showing evidence of having been 
water-rolled and worn before being imbedded, and consequently are always 
more or less broken and imperfect at the upper margin. The specimen of 
medium size figured is from the collection Acad. Nat. Sci. Phila. Those 
represented by Figs. 8 and 9 are in the Am. Mus. Nat. Hist., and the others 
are from Rutgers College collection. | 
BELEMNITES ? AMBIGUUS. 
Belemnites ? ambiguus Morton: Synopsis, p. 35, Pl.1, Figs. 4, 5. 
I have not been able to find Dr. Morton’s type specimen of this species, 
which he describes as “straight, elongated, quadrangular, striated longitu- 
dinally; front convex; back flat; sides slightly depressed by a longitudinal 
