CRETACEOUS PERIOD. 479 



B. Later Cretaceous. — No. 4 (Pierre group). Upper Missouri: Nautilus 

 Dekayi, Ammonites Placenta, A. complexus, Baculites ovatus, B. compressus, Heli- 

 coceras Mortoni, Inoceramus sublevis, Mosasaurus Missouriensis. Alabama : 

 In bed a, Teredo tibialis ? ; in bed b, Exogyra costata, Gryphsea vesicularis, 

 Inoceramus biformis, Pecten b-costatus, Nautilus Dekayi, Ammonites Placenta, 

 A. Delawarensis, Baculites ovatus; in bed c, Ostrea Larva, Gryphsea lateralis 

 (G. Vomer), Neithea Mortoni. New Jersey: Bed a, Ammonites Placenta, Bacu- 

 lites ovatus; bed b, Amm. Delawarensis, A. complexus, Baculites ovatus, Nautilus 

 Dekayi, Belemnitella mucronata ; bed c, Terebratulina plicata, Pholadomya 

 occidentalis, Ostrea Larva, Gryphsea vesicularis, Exogyra costata, bones of Mosa- 

 saurus. 



No. 5 (Fox Hills group). Upper Missouri : Nautilus Delcayi, Amm. Placenta, 

 A. lobatus, Scajyhites Conradi, Bactdites ovatus, Mosasaurus Missouriensis. 

 Alabama: Exoyyra costata, Gryphsea vesicularis, Nautilus Dekayi, Baculites 

 ovatus, Scaphites Conradi. New Jersey: Montlivaltia Atlantica, Nucleolites 

 crucifer, Ananchytes cinctus, A.fimbriatus, Terebratula Harlani, Gryphsea lateralis, 

 G. vesicularis, Neithea 3Iortoni. 



The New Jersey region abounds in Oysters and Exogyrse, has some Ammonites, 

 Bactdites, and Echinoderms, but no Hippurites or Caprinse. 



The Upper Missouri has very few Oysters, no Exogyrse, many and large Am- 

 monites and Baculites, but one rare Echinoderm [Hemiaster Humphreysianus), no 

 Brachiopods, except two Lingulse, and no Hippurites or Caprinse. 



The Alabama resembles the New Jersey, and the Arkansas the corre- 

 sponding or middle beds of Nebraska and upper of New Jersey; but both con- 

 tain Hippurites and Echinoderms. 



The Texas region has but few species in common with the others, — Ammonites 

 vespertinus, Inoceramus latusf, and/. Barabini, the latter being still questioned; 

 and it is characterized by Hip>purites, Caprinse, Nerinsese, etc., like the Upper 

 Chalk of southern Europe. 



The species common to Nebraska and New Jersey, according to Meek & Hay- 

 den, are Nautilus Dekayi, Scaphites Conradi, Ammonites Placenta, A. complexus, 

 A. lobatus, Baculites ovatus, and Amauropsis paludinseformis. 



2. FOREIGN. 

 I. Rocks : kinds and distribution. 



The Cretaceous formation covers a large part of southeastern 

 England eastward of the limit of the Jurassic, from Dorset on the 

 British Channel to Norfolk on the German Ocean ; and also a nar- 

 row coast-region about, and south of, Flamborough Head. (Map p. 

 354.) Like the Jurassic, it reappears again in northern France, 

 across the British Channel. It also occurs in other parts of France, 

 in Sweden, and in southern, central, and western Europe. 



The rocks are (1) Sandstone, generally soft, and of various colors; 

 (2) Marly or clayey beds; (3) the variety of limestone called 

 Chalk, the common writing-material, in beds of great thickness ; 



