CRETACEOUS PERIOD. 



477 



((£.) Gasteropods. — Fig. 758, Fusus Newberryi M. & H., from Nebraska; fig. 759, 

 Fasciolaria buccinoides M. & H., from Nebraska; fig. 760, Aporrhaist Americana 

 ( — Rostellaria Americana) Evans & Shumard, from Nebraska; fig. 761, Mar- 

 garita Nebrascensi8 M. & H., from Nebraska; fig. 762, Nerinsea Texana Roemer, 

 from Texas; N. Acus Roemer, from Texas; figs. 763, 764, Bulla specioaa 

 M. & H., from Nebraska. 



(e.) Cephalopoda. — Fig. 765, Ammonites Placenta Dekay, from Atlantic border, 

 Gulf border, and Upper Missouri, young specimen, natural size; fig. 765 a, out- 

 line side-view of the same, reduced; fig. 765 b, one of the septa of the same, 

 natural- size ; fig. 766, Scaphites Conradi Morton, from the same localities as pre- 

 ceding; fig. 767, S. larvseformis M. & H., from Nebraska; fig. 768, Baculites 

 ovatus Say, from New Jersey ; fig. 768 a, outline of section showing oval form ; 

 fig. 769, outline of section of B. compressus Say, Upper Missouri; fig. 770, Nau- 

 tilus Dekayi Morton, from the Atlantic and Gulf borders, and west of the 

 Mississippi from Texas to Upper Missouri, and also reported from Europe, 

 Chili, and Pondicherry in the East Indies. Fig. 771, Belemnitella mucronata 

 Schlotheim, same U. S. distribution as preceding. 



Fig. 771. 



Cephalopod. — Belemnitella mucronata. 



4. Vertebrates. — (a.) Fishes. — Fig. 772, Otodus appendicular, from New 

 Jersey. This genus Otodus (of the tribe of Squalodonts) is near Carcharodon, 



Figs. 772, 773. 



Squalodont Selachian. — Fig. 772, Otodus appendiculatus. Cestraciont Selachian.— 

 Figs. 773, 773 a, Ptychodus Mortoui. 



but the teeth have a smooth margin without denticulations. Oxyrhina, an» 

 other genus of this period, is like Otodus in this respect, but wants the small 

 lateral teeth a, a. There were also species of Lamna, the teeth of which are 



