Part II - State of New Jersey

152 CRETACEOUS FOSSIIJSlonga in these same respects (see pl. 79, fig. 5a). It cannot be too stronglystressed, however, that at least some juvenile guards of B. americana..szrbfusiformis are indist,inguishable from the more slender andlonger jnrenile guard types occurring in 1:. amoricana var. americanaand that the number of the guards of both varieties studied in this respectis insufficient for any definite conclusions on the subject.Dktribzitwn and Stratiprapi~ica' Runye.-Within the state of NewJersey B. americnna rar. s~rbfi~sifor~~zts, and the guards transitionalbetween it and other varietias of the species, have been encountered inalmost eyery one of the localities from which belemnite collections harebeen studied by the ~riter; it is, however, absent from such localitiesas Barnsboro and Glassboro, New Jerscy, and Reedy Point, Delaware,which is probably owing to t,he small amount of the gnards availahle(1 to 7) from these localities.The writer has seen specimens of R. americana var. subfusiforntisfrom the Nount Laurel sand as n7ell as from the Navesink marl, whichseems to indicate that it has the same stratigraphieal range as the restof the varieties of t,he species.B. anlericana var. svbfusiformis is a rare form at most of its localities.Only from 1% to 15.20% of the guards have been found to hereferable to it at most of the localities studied.Range in New Jersey-JIOUNT LAUREL: Xutt Farm.NAVESINIC: Cream Ridge, Arneytown.Range oatside New Jersey-Chesapeake and Dela\xran: Canal between Reedy Point and St.Georges (Mount Laurel-Yavesink) ; Bohemia Mills, Maryland.Affinities and Differences.-The reduced value of the Schatsky Indexappears to be one of the r~~ost reliable (listinetinns between B. americnnarar. sitbfusifor~~bis on the one hand and R. nmericana var. americasa.R. a~~~erieunn var. .i11ter11ier7,ia, and 8. a~~rericana nov. var. indet.Tar. A and B on the other. There even seem to be relatively few specimens,that are transitional betmecn both groups of forms in this respect,.Also the pronouncedly laneeolate outline of its guard in ventral aspectand n~ostlyfeebly lanceolate outline in lateral nspeet readily distinguishR. an~ericann var. sabfiisifornlis from all other varieties with the eseeptionof B. amcricana var. interntedia. This latter variety is, however,distinct from B. omoricana var. subfusiforz~lis in its greater valueof the Schatsky Index, its much deeper alveolus, and in the acute, long:and almost nonmueronate outline of the apical end of its guard. Theshallower alveolus is also helpful in the differentiation of l3. antericannTar. subfusiforrnis from other varieties of the species.From B. anterica?aa Tar. polita nov. var., B. anzcrica?~a var. szrbftraiformisdiffers in the presence of relatively strongly developed sculptureof the surface of the guard, in its relatively much smaller, shorter, andNEW JERSEY GEOLOGICAL SURVEY