39-1 Systematic Paleontology 



on the dorsal side a broad flattened ridge; phragmocone nacreous, and 

 provided with a single dorsal ridge and a ventral process, and often with 

 a minute bulb at the apex."— Meek, 1876. 1 



The genus is restricted in its distribution to the Middle and Upper 

 Mesozoic. 



Belemnitella Americana (Morton) 

 Plate XII, Pigs. 4-6 



Belemnites subconicus Morton, 1828, Jour. Acad. Nat. Sci., Phila., 1st ser., 



vol. vi, p. 91, pi. v, fig. 7. (Not B. subconicus Lam.) 

 Belemnites americanus Morten, 1830, Am. Jour. Cci., 1st ser., vol. xvii, p. 



281; vol. xviii. pi. i, figs. 1-3. 

 Belemnites americanus Morton, 1830, Jour. Acad. Nat. Sci., Phila., 1st ser., 



vol. vi, p. 190, pi. viii, figs. 1-3. 

 Belemnites americanus Morton, 1834, Syn. Org. Rem. Cret. Group, U. S., p. 



34, pi. i, figs. l-3a. 

 Belemnitella americana Emmcns., 1858, Rept. N. C. Geol. Survey, p. 246, 



fig. 101. 

 Belemnitella paxillosa Meek, 1864, Check List Inv. Fossils, N. A., Cret. and 



Jur., p. 26. 

 Belemnitella mucronata Conrad, 1868, Cook's Geol. of New Jersey, p. 375, 



figure; p. 731. 

 Belemnitella paxillosa Conrad, 1868, Ibidem, p. 731. 

 Belemnitella americana Whitfield, 1892, Mon. U. S. Geol. Survey, vol. xviii, 



p. 280, pi. xlvii, figs. 1-11. 

 Belemnitella americana Roberts, 1895, Johns Hopkins Univ. Circ, vol. xv, 



No. 121, pp. 16, 17. 

 Belemnitella americana Johnson, 1905, Proc. Acad. Nat. Sci., Phila., p. 28. 

 Belemnitella americana Weller, 1907, Geol. Survey of New Jersey, Pal., vol. 



iv, p. 839, pi. cix, figs. 1-4. 



Description. — " Stylet or guard rather large, solid and heavy, often 

 becoming thickened with age so as to be proportionally much larger in 

 diameter as compared with smaller individuals. Specimens varying from 

 :l in. to nearly 4 in. in length below the base of the slit, the larger 

 ones evidently having a length of fully 6 in. from the lower extremity to 

 the top of the internal cavity or conotheca. General form triangularly 

 cylindrical in the upper part, becoming flattened on the ventral side in the 



1 Rept. U. S. Geol. Survey, Terr., vol. ix, p. 501. 



