CAMBRIAN GEOLOGY AND PALEONTOLOGY 



II 



No. 13.— DIKELOCEPHALUS AND OTHER GENERA OF 

 THE DIKELOCEPHALIN^ 



By CHARLES D. WALCOTT 



(With Plates 60 to 70) 



CONTENTS PAGE 



Introduction 346 



Classification 347 



Observations on the genera 348 



Synonymic references 349 



Stratigraphic position of the DikelocephaUnse 353 



Table of Upper Cambrian formations 353 



Table of pre-Ordovician formations 354 



Jordan formation 355 



Fauna 355 



St. Lajivrence formation 355 



Fauna 356 



Franconia formation 357 



Fauna 357 



Fauna of Eau Claire formation 358 



Stratigraphic range of the genera 358 



Dikelocephaltis 359 



Saukia 360 



OsceoUa 362 



Calz'inella 362 



Conokephalina 362 



Description of genera and species 363 



Genus Dikelocephalus Owen 363 



Dikelocephalus ? dalyi, new species (pi. 64, figs. 1-5) 367 



Dikelocephalus hartti (Walcott) (p\. 63. figs. 1-7, ya) 368 



Dikelocephalus ? limbatiis Hall (pi. 65, figs. 5-8) 369 



Dikelocephalus niiniiesotensis Owen (pi. 60, figs. 1-8; pi. 61, 



figs. 1-3, 5-7 ; pl- 62, figs. 4-6 ; pi. 65, fig. i) 369 



Dikelocephalus minnesotensis var. (pl. 61, fig. 4) 371 



Dikelocephalus iexanus, new species (pl. 65, fig. 4) 372 



Dikelocephalus " tribulis Walcott (pl. 63, figs. 8-10, loa).... 372 



Dikelocephalus vanhornei, new species (pl. 62, figs. 1-3) 373 



Dikelocephalus, species undetermined (footnote^) 391 



Genus Saukia, new genus 373 



Saukia coloradoensis, new species (text figs. 13-16) 376 



Saukia crassimarginata (Whitfield) (pl. 61, fig. 8; pl. 65, figs. 



9, 10 ; pl. 66, figs. 2-5, 5a) 377 



Saukia fallax, new species (pl. 67, figs. 21, 21a, 22, 22a) 378 



Saukia junia, new species (text fig. 17) 378 



Saukia ?? leptcenarum (Wiman) 379 



Smithsonian Miscellaneous Collections, Vol. 57, No. 13 



- . 345 



