TRILOBITA—OPISTHOPARIA. 



305 



130. G. portlocki Meek and Worthen. Mississippic. 



Cephalon broadly rounded, the flattened border confined to the 

 side; genal spine short; basal lobes of glabella small, depressed. 

 Eyes small, in the form of oval tubercles and isolated from the 

 much depressed palpebral lobes. Thorax with axis slightly wider 

 than a lateral lobe. Pygidium about a fourth wider than long, 

 with a rather narrow, flattened margin; outline as of G. scitiila. 

 Entire test granular. One specimen measures in length of cepha- 

 lon, thorax and pygidium respectively 9.5, 11 and 11 mm.; width 

 of thorax 22 mm. 



Keokuk of Illinois, Missouri, Iowa and Nevada. 



Fig. 161 6. a, b, Griffithides sanga- 

 tnottensisy cephalon and pygidium ; c-e, 

 G. scitubis, three views of an enrolled 

 specimen. (Tnd. Surv.) 



Fig. 1 61 7. Bronteus lunaius. 

 (After Logan.) 



131. G. scitulus Meek and Worthen. (Fig. 1616, c-^.) Carbonic. 

 Small. Genal spines reaching back to the fifth thoracic segment. 



Cheeks small in comparison with eyes and glabella. Whole sur- 

 face granular. 



Widely distributed in the Coal Measures of the United States. 



132. G. sangamonensis M. and W. (Fig. 1616, a, ^.) Carbonic. 

 Diflfers from G. scitulus in its larger size, more regularly rounded 



anterior cephalic margin and more pointed or subtriangular 

 pygidium. 



Coal Measures of Illinois. 



