LIST OF ILLUSTRATIONS xiii 



FIGURE PAGE 



123. Paleogeographic map of North America during Triassic time . . . 207 



124. The steep western front of the Holyoke Range as seen from East- 



hampton, Massachusetts 209 



125. Sketch map showing the relation of land and water in Europe in 



the early Triassic 211 



126. Parts of a Triassic Conifer, Voltzia heterophylla 213 



127. A Triassic Ceratite, Ceratites trojanus, with part of shell removed 



to show suture structure 214 



128. A Triassic long- tailed Macruran Decaped, Pemphix Sueurii ... 215 



129. A Ganoid, Catopterus redfieldi, from the Triassic sandstone of 



Connecticut 216 



130. Tracks of a small two-legged Dinosaur on a slab of Triassic sand- 



stone from the Connecticut Valley 216 



131. Tracks of a large two-legged Dinosaur on Triassic sandstone from 



the Connecticut Valley, showing how both feet slid some dis- 

 tance in the soft material after which the creature suddenly sat 

 down, the end of the backbone having left a distinct impression. 217 



132. Structure section through a portion of the central Sierra Nevada 



Mountains, exhibiting the highly folded character of the Jurassic 

 and late Paleozoic rocks 220 



133. Paleogeographic map of North America during late Jurassic 



time 222 



134. Sketch map showing the relations of land and water in Europe 



during late Jurassic time 224 



135. A living Cycad, Dioon edule, of Mexico 226 



136. A fossil Cycad tree trunk, Cycadeoidea pulcherrima 227 



137. Jurassic Cycad leaves 228 



138. A Jurassic Crinoid, Pentacrinus fossilis 229 



139. A regular or radially symmetrical Echinoid, Pseudodiadema 



texanum, of Lower Cretaceous age 229 



140. An irregular or bilaterally symmetrical Echinoid, Hemiaster tex- 



anus, of Cretaceous age 230 



141. An Ammonite with part of shell removed to show the very com- 



plicated (frilled) sutures 230 



142. Internal shell of a Belemnite, restored 231 



143. A Jurassic Belemnite, Belemnoteuthis antiqua 231 



144. A Jurassic long-tailed Decapod (Macruran) 232 



145. Three stages in the life history of a modern Crab 233 



146. A primitive or ancestral Jurassic Teleost, Hypsocormus insignis . 233 



147. The earliest known Bird, Archeopteryx macrura, from the Jurassic. 234 



148. Map showing the surface distribution (areas of outcrops) of Lower 



Cretaceous strata in North America 238 



149. Map showing the surface distribution (areas of outcrops) of 



Upper Cretaceous strata in North America 239 



150. Paleogeographic map of North America during Lower Cretaceous 



time 245 



151. Paleogeographic map of North America during Upper Cretaceous 



time 247 



152. Typical exposure of Upper Cretaceous (Selma) chalk in Alabama. 248 



