Part II - State of New Jersey

Sometimes the ventral fissure reaehes the surface of the guard at thelevel of the embryonic bulh or even somcwhat below this latter. Insome instances irregularly bent (see pl. SI): fig. 3a) or straight bottomsof ventral fissure running very ol)liquely ul)mard and forming angles ofonly 5-lj015-it11 tl~e inner xvall of the alveolus (see pl. 77, fig. 5e) dsooccur. All the extremes are connected by numerous transitions with oneanot,l~cr ancl with the al~ove (lcscribed predominant type of the outline.The median line ;11\~ays runs closer to the ventral side of the guard,being as a rule two-fifths of the thickness of the gnard away from thislatter. Its course is com~nonly quite to almost straight within the anteriort,hrec-quarters of the postalveolar part, of the guard hut it deviatesslightly toward t,llc median plane of the guard in the apicalquarter of the same. Therefore t,he rnrtcro nearly ;~l~vays lies withinihe median plane of the guard or eseeetlingly close to this latter.The alveolar fissure is always long in relation to the depth of theal~,eolus. In the majority of the guards studied it reaches well into theposterior third or quarter of the alreolns (pl. 79, figs. lc, 2, 3a, 6e, 7).The goar(ls in 11.11icl1 tltc alveolar fissure ends somewhat bclo~v tlle mi&dlc of the alveolr~s (sce pl. 76> fig. 2; pl. 77, fig. 2b) are uncommon, andthose in \rhieh the fissnrc (locs not reach t,he middle of the alveolus areexceerlingly rare. At the salne time the inst;~nces when the ventralfissure reachcs the snrfacc of the gnard only 3-6 mm. above the levelof the embryonic bulb are qnite comlnon (pl. 79, figs. lc, 2) ; sometimesthe rentri~l fissure even re:~cl~es the surface of the guard at the levelof the enlliryonic bulb.Jocf~lities, Geographicf~l a1uI Str(itigrnpkku1 Rang" Belo)rt~~mitellnaw~ericn~ra (Norton) v;lr. on~cricnna nov. var. forms from 60% to 95%of the populations of B. n~iiericana (Morton) in almost all belemnitecolleetions from Nev Jersey, Delam7are and Maryland which wercstnclied by the \vriter. Only the lot 174796 USNhl is dominated byt,r:~nsitional forms betv.ecn K. americnntb var. sz~bf11siforn1i.9 and var.longa. Only one gnarcl out of five can be referred to B. anrericana var.a)neric(~na in this lot.B. a)nericana va~.. a~nevi~(ina ;tplicars to be ahout equally nnmerousin the JIount Laurel sand and in the Navesink marl; its representativesfrom the two formations are indistingr~isl~able. It is possible,ho\vever, that extensive ,bed by l~e(l collecting woulcl show that specimensof 11. a)~~erieon~r from the hIo1unt La~~rel sand are somewhat moreslencler ancl possess longer, more acnte, and less distinctly mucronate;~l?ical ends of tl~c goartl, ;~nd have a smaller value of the Sehatsky Index,than thosc from the N;~vcsink marl.Tl~e geographic;~l range of n. anloricnnn var. antaricana appears tocoinei~le vith that of other describc~l val.ict,ies of the species.NEW JERSEY GEOLOGICAL SURVEY