INDEX 493 



PAGE 



Trematobolus excelsis, new species 80, pi. 8, fig. 8 



compared with Dearbornia clarki 80 



stratigraphic position and association -'iSy, 188 



Trematobolus insignis, compared with Trematobolus excelsis 80, 81 



Trematobolus kempanum. compared with Trematobolus excelsis 80, 81 



Trematobolus pristinus, mentioned 81 



tricenaria, see Orthis. , 



Trilobite, a mud-burrowing animal similar to Limulus 241-242 



Trilobites, evolution of 256-257, 260 



eyes of compared with those of the Isopoda 240* 



eyes of compared with those of Limulus 239 



Trimerella, nature of shell substance 150 



Trimerella lindstromi, mentioned 74 



Trimerella linguloides, mentioned 75 



Trimerellidse, evolution of 144 



mentioned 7Z 



Trinity Bay, fossils from 280 



triplicatella, see Orthis. 



Trois Pistoles, fossils from 339 



Troy, fossils from 274, 310 



troyensis, see Fordilla. 



TumbyhoJm, fossils from 292 



Turner, H. W., bibliographic reference 2ig 



cited 185 



turneri, see Acrothele. 



typa, see Ozvenella. 



typicalis, see Schizambon and Zacanthoides. 



Uinta Mountain uplift, mentioned 191 



Ulrich, E. O., acknowledgments 141 



ulrichi, see Acrotreta. 



Umbo, defined 159 



Umbonal cavity, defined 159 



Umbonal slopes, defined 159 



Umbonal muscle, defined 159 



unxia, see Syntrophia. 



Upper Cambrian, brachiopod genera occurring in pi. 11 (pp. 140-141) 



urania, see Linnarssonella. 



Utah, boundary of Cambrian land area in 168 



measurement of Blacksmith Fork section 5 



Pioche formation in 12 



relation of Brigham formation to the Flathead sandstone of Mon- 

 tana 8 



relative position and thickness of Cambrian formations in House 



Range 9 



relative position and thickness of Cambrian formations in north- 

 eastern part 6 



Utah and British Columbia, connection between sections in 169 



utahensis, see Micromitra (Paterina) labradorica. 



