284 



NORTH AMERICAN INDEX FOSSILS. 



XXXIII. DiKELLOCEPHALUS Owen. 

 Cephalon semicircular, flat. Glabella oblong, with parallel sides 

 and marked by three furrows of which the posterior two cross the 

 glabella. Thorax with nine segments; 'axis narrower than the lat- 

 eral lobes. Pygidium with a flattened border which is rounded in 



Fig. 1585. Crepicephahis 

 augusta, cephalon and py- 

 gidium. (After Walcott.) 



Fig. 1586. Crepicephalus texanus, X /^» partly 

 restored, (After Walcott.) 



the middle and produced laterally into a backward pointing projec- 

 tion on each side. Axis of pygidium extending only half its length 

 and with four to six segments. Cambric. 



73. D. minnesotensis Owen. (Figs. 1587, a, b ; 1588, a, b.) Cambric. 

 Very large. Glabella almost flat. Form as shown in figures. 

 Upper Cambric (St. Croix) of Minnesota, etc. 



74. D. osceola Hall. (Fig. 1589.) Cambric. 

 Small, length of head one half inch or less. Eyes near glabella. 



Anterior to glabella is a broad groove with an abruptly elevated 

 narrow border. 



