282 PALEONTOLOGY OF NEW JERSEY. 



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

 the fibers being very shghtly 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 tlie 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 been 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 oiitcrops of 

 that bed throughout the State, and is abundant at many. Marlboro, Free- 

 hold, Creamridge, MuUica 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, PI. i, 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 



