CRETACEOUS PERIOD. ' 469 



lites ovatus, Nautilus Dekayi, Belemnitella mucronata ; bed c, Terebratulina plicata, 

 Pholadomya occldentalis Mort., Ostrea larva, Gryphcea vesicularis, Exoyyra costata, 

 bones of Mosasaurus. 



No. 5 (Fox Hills group). Upper Missouri: Nautilus Dekayi, Amm. placenta, A. loba- 

 tus Tuomey, Scaphites Conradi, Baculites ovatus, Mosasaurus Missouriensis. Alabama: 

 Exoyyra costata, Gryphcea vesicularis, Nautilus Dekayi, Baculites ovatus, Scaphites Con- 

 radi. New Jersey: Monti ivaltia Atlantica, Nucleolites crucifer, Ananchytes cinctus, 

 A. fimbriates Mort., Terebratula Harlani, Gryphcea luteralis, G. vesicularis, Neilhea 

 Mortoni. 



The New Jersey region abounds in Oysters and Exogyrce, has some Ammonites, Bacu- 

 lites, and Echinoderms, but no Hippurites or Caprince. 



The Upper Missouri has very few Oysters, no Exogyrce, many and large Ammonites 

 and Baculites, but one rare Echinoderm (Hemiaster Humphrey sianus M. & H.), no 

 Brachiopods, except two Lingulce, and no Hippurites or Caprince. 



The Alabama beds resemble the New Jersey, and the Arkansas the corresponding 

 or middle beds of Nebraska, and upper of New Jersey ; but both contain Hippurites 

 and Echinoderms. 



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

 vespertinus, Inoceramus latus (?), and /. Barabini, the latter being still questioned; and 

 it is characterized by Hippurites, Caprince, Nerincece, etc., like the Upper Chalk of 

 southern Europe. 



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

 are Nautilus Dekayi, Scaphites Conradi, Ammonites placenta, A. complexus, A. lobatus, 

 Baculites ovatus, Amauropsis (?) paludinceformis M. & H. 



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 narrow 

 coast-region, about, and south of, Flamborough Head, as shown on the 

 map, p. 344. 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 and central Europe, covering 

 much of the territory between Ireland and the Crimea, 1,140 miles in 

 breadth, and, between the south of Sweden and south of Bordeaux, 

 840 miles. (Lyell.) 



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

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

 Chalk, the common writing material, in beds of great thickness ; (4) 

 other limestones, either loose or compact. Among the sandy por- 

 tions, the Green-sand beds are a marked feature, especially of the 

 lower part of the formation. This is so eminently the fact that the 

 Lower Cretaceous in England is called the Green-sand, although only 

 a part of the layers are green, and in some regions none at all. 



The Chalk often contains flint, in nodules, which are distributed in 

 layers through it, like the hornstone in earlier limestones. Though 

 generally more or less rounded, they often assume fantastic shapes, 



