32 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48 



Description. — Glabella with totally undifferentiated occipital ring 

 defined by an exceptionally deep axial furrow, strongly convex trans- 

 versely, unfurrowed, slightly narrowed from the occipital ring to the 

 level of the posterior third, then slightly expanded forward, sharply 

 narrowed and somewhat pointed in front, reaching the border fur- 

 row. Cheeks very convex, posteriorly overhanging the border furrow, 

 anteriorly separated by a narrow (tr.) preglabellar depression formed 

 by the merging of the axial and border furrows. Border strongly 

 convex, fairly wide, defined by a deep border furrow, contributing 

 to the great relief of the cephalon. Tubercles on the border moder- 

 ately elevated, generally seven or eight pairs present, about equally 

 spaced. Posterior border furrow deep ; posterior border straight from 

 axial furrow to sharp geniculation which is located not far from genal 

 angle and is marked by a short spine. A characteristic feature of 

 the border is a very narrow, shallow furrow parallel and close to the 

 posterior margin that sets off a slight, obtuse expansion. The artic- 

 ulated specimen shows that this feature corresponds to a similar 

 one at the fulcrum of the anterior margin of the first thoracic seg- 

 ment. However, the geniculation of the posterior cephalic border 

 with its spine is situated farther outward. In front of the spine the 

 cephalic border curves downward and forward to join the lateral 

 border which as usual is at a lower level ; no sharp angle is formed, 

 and the cephalic border is narrowest at this point. 



First thoracic segment with anterior margin distally from the above- 

 mentioned fulcrum sharply bent backward to form a well-developed 

 facet. Axis not preserved. Second segment showing a very convex 

 axial lobe and deep axial furrow. Pleural articulation between first 

 and second segment with features similar to those present between 

 the cephalon and the first segment, but more distally located. Anterior 

 margin beyond the geniculation bent downward but not backward. 

 Posterior margin with geniculation situated still farther outward, dis- 

 tally strongly bent forward and downward. Third thoracic segment 

 not preserved. 



Pygidium with strong relief. Axis prominent, defined by deep axial 

 furrow, convex in both directions, totally unfurrowed, not quite 

 reaching the border furrow. Articulating half -ring expanded medially 

 by a rearward median inbend of the articulating furrow. Axis bearing 

 a strong median spine at about four-fifths of its length ; this spine 

 is broken off in all pygidia except one specimen where it could be 

 partly restored. Pleural regions strongly convex, near posterior end 

 forming a narrow, convex band between the end of the axis and the 

 border furrow. Border furrow deep ; border narrower than in cepha- 



