index 557 



PAGE 



Apus 371, 386, 393 



attachment of limbs 159 



compared with Neolcnus 129 



Triarthrus 136, 141, 170 



Triarthrus becki 204 



trilobite 125, 163, 167, 169 



lucasana Packard, discussed 208 



figured, pi. 36, fig. 4 208 



Archzocyathus (Archceocyathellus) atreus Walcott, described 67 



figured, pi. 8, figs. 2, 2.a 104 



Arctomys formation (Cambrian, Upper) 461 



fauna 462 



Asaphellus 470 



euclides Walcott 473 



Asaphidae Burmeister 132 



Asaphinse Raymond 132 



Asaphiscus, trails 175 



Asaphus f sp. undt 474 



Asteractinella Hinde 326, 328 



Astraeospongia Roemer 322, 323 



Attachment of ventral limbs to dorsal test (Neolenus serratus Walcott) . . 382 



Barrande, description of trilobites 123, 124 



intestinal canal of trilobite 157, 158 



Bassler, Dr. R. S 366, 368, 369, 371, 380, 389, 435, 470 



Bathydorus uncipe F. E. Schulze 297 



Bathyuriscus 11 



cf. rossensis Walcott, described 46, 49 



figured, pi. 5, figs. 5, 5a-d 54 



pi. 5, figs. 6, 6a 55 



(Poliella) chilo Walcott, described 50 



figured, pi. 5, fig. 4 54 



sp. undt. 1 48 



trails 175 



Beaverfoot formation (Silurian ?) 463 



fauna 463 



Range 463 



Beecher, Dr. Charles E 126, 136, 137, 138, 140, 141, 142, 153, 154, 164, 



165, 167, 169, 170, 376, 378, 396, 414, 415, 416, 



417, 424, 429 



Bellerophon ? lavassa Walcott 473 



Bernard, cited on Apus and the trilobites 167 



Beyrich, Prof., intestinal canal of trilobite 157 



Bibb formation (Lower Ozarkian) 469 



Billings, discussion of Isotelus covingtonensis 134 



Billings Butte 458 



fauna 471 



