PALJBONTOLOGY OF ILLINOIS. 



large, subtrigonal or tuberculiform, and entirely isolated 

 by the distinct lateral furrow passing obliquely across with 

 a backward curve, from opposite the middle of each eye, so 

 as to intersect the neck furrow, second lateral lobes much 

 smaller and more obscure than those behind, and also 

 oblique, being merely defined by a faintly impressed, 

 curved, oblique line; in advance of these there are also 

 obscure indications of two other short, nearly obsolete 

 lateral furrows, scarcely visible without the 'aid of a lens. 

 Occipital segment well defined, but lower and considerably 

 shorter in its transverse diameter than the glabella; strongly 

 arched upwards (not forward) and projecting backwards a 

 little behind the posterior line of the cheeks ; neck furrow 

 distinct, and arched upward wilh the occipital, or neck seg- 

 ment; its continuation along the posterior sides of the 

 cheeks very deep, and nearly straight for about two-thirds 

 of the way across towards the lateral margins, where it 

 intersects another furrow or depression coming around the 

 sides of the cheeks. Eyes lunate, rather large, or nearly 

 half as long as the glabella, exclusive of the neck seg- 

 ments, prominent, but not as high as the glabella, located 

 about half their own length in front of the posterior 

 margin of the cheeks; visual surface smooth, or even ap- 

 parently polished, and showing no traces of lenses 

 under a good magnifier; palpebral lobes convex, but 

 resting like a lid upon each eye. Cheeks sub-trigonal, 

 declining abruptly from the eyes; lateral margins turned 

 downward, and forming below a sharp edge, which con- 

 tinues back along the lower margin of the posterior 

 spine-like appendages; above this there is a vertically flat- 

 tened, or even concave zone or belt, extending from near 

 the front part of the glabella around the outer side of each 

 cheek, and becoming a shallow furrow as it passes back 

 upon the spines, along which it seems to be more or less 

 marked nearly to their pointed extremities; between this 

 vertically flattened band and the eyes, there is another 



