Part II - State of New Jersey

ounded short apical entl with or without well defined muero (see pl.77, fig. 3a; pl. 79> fig. Ga). These estrcmes of the ventral outline of t,heguard connect 11. aa~ericnlia rar. anlerica?~~ wit11 L-'. n~rlei.icana var.ionya, B. an~oriec~na var. sl~bfi~siformis, B. americu~~i~ var. i,~iter~~lcciin,and also with the younger species E. ef. bz~lbosa Afcclc and Hayden.In the majority of the specimens studied, the ventral i~nd dorsalsides of the guard are fairly to very strongly flattened, either tl~roughouttheir entire length or? at least, hctweeu the base of the ventral fissureand the apical end of the guard. This flattening generally increasesgradually tolr.ard the apical end of the guard and results in thepronouncedly oval cross sections of the guard all over its posterior halfto two-thirds (see pl. 7G> fig. le; pl. 77, fig. 3c; pl. 79, figs. ld, 3h, 5b).Tile dorsal side of the gaartl is often more strongly flattened than theventral side. In a number of guards, including the leutotype of thespecies, it is virtually flat (see pl. 76, fig. le; pl. 79, figs. Id, 3b). 'rhexrentral side of the guard only rarely beco~ncs con~pletely flattened. Thedorso-ventral diameter is comluonly larger tl~an tlie lateral diameter at,the base of tlie alveolar fissure and further orad. There are, ho~ve~er,quite a few guards in which this relationship is reversed, and somewith hot11 diameters virtually equal. As t,he allore (leserihed dorsoventralflattening of t,he guard is accomp;~nic(l 11y its market1 (lorsoventralcompression below the level of (,he alveolar fissure, the dorsoventraldiameters are alrvays markedly less than the lateral ilialnetersat the same levels throaghout this part of t,hc guard (see pre\rio~islylisted cross sections of the guard). Tn tho ~najority of the specimens thecross section of the guard at its alveolar rim is either almost perfect,lyround or feebly oval with the lateral di;lmeter still somewhat exceedingthe dorso-ventral cliameter. In rarer instances the dorso-ventral iliametersligl~tly cseeeds the lateral one at the alveolar rim. Even in theseinstances, ho~vever, this relationship often bccornes reversed above thelevel of the base of the ventral fissure. The other more common estremcis represented by the guards 1aBie11 are pronouncerlly (lorso-ventrallyflattened and colnpressed even at their t~lvcolar rim. The leetotype ofthe species (see pl. 76, figs. la-lcl) sl~o\~s this relationship.Over the anterior two-t,hir(ls to three-quarters of the length of theguard its markedly flattened dorsal surface is situated between t,hcdorso-lateral depressions of the nsnal Eclemnitellidac type. At theirbottoms these depressions commonly earry indistinct cloahle dorsolateralfurrows (or secondary depressions) separated 11y ;I lorn longitudinalridge. Ilorso-lateral depressions run generally longitudinallybut they converge more or less marlredly toward the median plane ofthe dorsal surface of the guard as they approach its alveolar rim. Thisgradually reduces the width of the flattenccl ilorsal side of the guardover its alveolar third. The ilorso-lateral ~leprcssions gradually becomeshallower apically unt,il they finally (1isal)pear ~vithin the apical thirdor quarter of the lellgtll nf t,he guard. Furthermore: the (loltble dorso.lateral forro~vs oeenrring i~t their lrotto~ns become 111ore an~l more shal-NEW JERSEY GEOLOGICAL SURVEY