162 



Contributions to Palaeontology. 



width throughout. Dorsal furrow strongly defined, and 

 continued in front of the glabella. 

 Fixed cheeks comparatively wide. 



Facial suture vertical from the contour line in front to 

 the inside of the palpebral lobe ; thence turning a little 

 outwards, it comes to the posterior margin halfway be- 

 tween the dorsal furrow and the outer margin of the 

 movable cheek. The frontal limb is somewhat abruptly 

 convex from the furrow, but never rises nearly so high 

 as the frontal lobe of the glabella, and is abruptly bent 

 downwards to the anterior margin. Eyes unknown. 



Movable cheek large, somewhat trapezoidal : the outer 

 limb is extremely thickened, with a few coarse longi- 

 tudinal stride preserved in the cast, extended behind, 

 and uniting with the thickened posterior border, it 

 forms a spine three-fourths as long as the body of the 

 cheek. Within the thickened border there is a distinct 

 groove, which is not quite united with the groove of 

 the posterior limb. 



Thorax strong ; axis elevated, and the extremities of the 

 annulations swelling into nodes : ribs strong, grooved 

 in the middle, and bent somewhat angularly backwards 

 in the middle. The anterior facette is abruptly turned 

 inward. 



Associated with the glabella? and cheeks, there are 

 several pygidia which appear to belong to the same spe- 

 cies. The specimen fig. 46 is somewhat paraboloid, the 

 axis strong and rounded, and marked by about four very 

 convex rings : the dorsal furrow is deeply impressed by 

 the lateral lobes rising abruptly, and becoming quite con- 

 vex in the middle, and thence curving downwards to a 

 narrow flattened border; marked by three ribs and an ob- 

 scure fourth one, which are grooved from near their 

 origin to the flattened limb. 



This species is common, and even abundant in some beds of 

 greenish gray sandstone at Trempaleau, and near the mouth of the 



