858 



CAMBEIAN BRACHIOPODA. 



Ogden Canyon, Utah, localities in 30p, 30q, 30s 



Ogof-ddu Cliff, near Criccietli, Wales, locality at 318s 



Ogygopsis zone (Middle Cambrian) discussed and fauna listed. . . 127-12S 



locality in. 14s 



mentioned 724 



Ogygopsis Jtlotzi, association mentioned 354 



Ojo de Agua, Argentina, locality at 389c 



Oklahoma, Cambrian species of, listed 114-119 



detailed section of Cambrian and Ordovician in, listing spe- 

 cies and localities 141-142 



localities in 9p-x, 9z, 12j, 12k, 12m, 12n, 12p 



Oksna, see Oxna. 



Old-age characters, discussed 315 



Olenelloides armatus, association mentioned 641 



Olenellus, association mentioned 338, 



340, 347, 349, 352, 583, 613, 617, 644, 659 



mentioned *j84 



OUnellusf, stratigraphic position of bowlder containing, dis- 

 cussed 454, 684 



Olenellus fauna, mentioned 362, 378, 387, 409, 492, 665, 681, 707, 731, 764 



Olenellus zone (Lower Cambrian) , localities in 142, 396v 



mentioned 473,584,620,701 



Olenellus gUberli, association mentioned 656 



thompsoni, association mentioned 316, 759 



mentioned 605 



Olenoides fauna, mentioned 362, 378 



Olenoides curtkei , association mentioned 692 



Olenopsis, association mentioned 584 



Olenopsis beds, mentioned 332 



Olenus, association mentioned 767 



mentioned 482, 766 



Olenus fauna, mentioned 657 



Olenus zone (Upper Cambrian), in generalized section for Swe- 

 den, Denmark, Finland, and Norway, listing species and 



localities 145 



localities in 9f, 309m, 390n 



mentioned 630 



Olenus truncatus zone (Upper Cambrian), localities in 310a, 310i 



mentioned 541 



Onaqui Range, Utah, locality in 33f 



onaquiensis, see Obolus ( Weslonia) ella. 



Oneida County, Idaho, localities in 4y, 5a-c, 5h, 54s-x, 55d 



" Oneota dolomite " (Lower Ordovician), localities in 339, 364a 



localities in, mentioned 169 



• Ontario, Cambrian species of, listed 114-119 



localities in 392b, 392d, 392e 



note on stratigraphic position of localities in ... : 143 



Ontika, Esthonia, Russia, locahties at 395d, 396k, 396q, 395t 



Oothkalooga Valley, Georgia, locaUty in 362 



Ophileta beds, mentioned 353b 



Ophir, Utah, localities near 3c-e, 329e 



ophirensis, see Acwtrcta and Micromitra (Iphidella) pannula. 

 ophirensis desccndens, see Acrotreta. 

 ophnensis rvgosa, see Acrotreta. 



Oquirrh Range, Utah, localities in 3c-e, 329e 



era, see Lingulella and Micromitra (Paterina) stissingen^s. 



"Orbicula bmhi," type of Keyserlingia 628 



"? crassa," discussed 594 



" reversa," compared with Keyserlingia buchi 630 



Orbiculoidea, described 722 



cardinal area discussed 305 



classification of 321,325 



evolution discussed 319 



evolution of 317 



general geographic and stratigraphic distribution of the 



species referred to 107 



general stratigraphic distribution and number of Cam- 

 brian species and varieties of ill 



listrium in 306 



muscle scars not shown in 313 



number of species of, in different types of sediment- . . 160 



reference to, of Orbiculoidea cotitraria, discussed 722 



reference to, of Orbiculoidea pileolus, discussed 723 



reference to, of Orbiculoidea varians, discussed , 723 



contraria, described 722 



general geographic and stratigraphic distribution 



tabulated 107 



type specimen figured PI. LXXXI, fig. 9 



Orbiculoidea pileolus, described 722 



general geographic and stratigraphic distribution 



tabulated 107 



type specimen figured PI. LXXXI, fig. 11 



varians, described 723 



compared with OrbicuMdea contraria 722 



general geographic and stratigraphic distribution 



tabulated 107 



type specimen figured PI. LXXXI, fig. 8 



Orbiculoides, compared with Discinolepis 664 



d'Orbigny, A., bibliographic reference 22 



Ordovician, Bohemia, generalized section, listing species and lo- 

 calities 124 



East Prussia, generalized section, listing species and localities 143 

 England, generalized section, listing species and localities ... 135 



families listed 113 



genera listed 113, 317 



Mount Bosworth, reference of, to Sherbrooke limestone 



explained 125 



Nevada, detailed section, listing species and localities 139 



Newfoundland, species and localities in, listed 140 



Oklahoma, detailed section of Arbuckle limestone 141 



Russia, generalized section, listing species and localities 143 



Scotland, generalized section, listing species and localities. . . 135 



species listed • 98-109 



species of Europe listed 123 



species of North America listed 122-123 



Utah, detailed section, listing included and correlated 



species and localities 148, 153 



Wales, generahzed section, Hsting species and localities 135 



See also Passage beds. 



Oregrund, Sweden, locahty near 311t 



orientalis, see Billingsella, Huenella, Micromitra {Paterina) labror 



dorica, and Y'orkia. 

 Original, see L'Original. 



Orleans Island, Quebec, locality on B6b 



ornaiella, see Micromitra (Iphidella). 



Orr formation (Upper Cambrian), in detailed section in House 

 Range, Utah, listing included and correlated species and 



localities 153-154 



localities in 30h, 30j-l, 30y, 31t 



mentioned 510 



Orr Ridge, House Range, Utah, locahties on 30h, 30j-l, 31t 



orta, see Acrothyra sigtutta. 



Orthacea, classification of 321, 325 



distribution in Cambrian strata 316 



genera and species referred to, described 725-795 



orthia, see Syntrophia. 



Orthidce, Cambrian and Ordovician types compared by UMch 308 



compared with Billingsella 749 



Billingsellidfe by Ulrich 308 



Cambrian Billingsellidas 320 



cruralium mentioned 309 



Ordovician and Cambrian types compared by Ulrich 308 



pseudospondylium discussed 307-308 



Schuchert on development of 308 



shell structure compared with that of Billingsellidae 300 



Ulrich on development, classification, and relations of 308 



Orthidse (Cambrian), compared with Ordovician Clitambonitidse 



by Uhich 308 



Orthis, classification of, by Ulrich 308 



compared with Billingsella 772, 773 



Eoorthis 772, 773 



Orusia 765 



Protorthis 739 



Wynnia 771 



cruralium mentioned 309 



discussed 772 



evolution discussed 320 



evolution of 317 



mentioned 735, 785, 788 



no Cambrian representatives 320 



presence at Hastings Cove mentioned 779 



pseudospondylium discussed 307 



reference to, of Eoorthis atava discussed 774 



sequivalvis, mentioned 772 



? armada, reference to Syntrophia discussed 798 



"barabuensis," mentioned 798 



