THE NATURAL HISTORY SURVEY. 273 



outline to the ends of the genal spines, with a flat, rounded, 

 median lip-like extension in front, the genal spines about two- 

 thirds the length of the head along its median line. Glabella 

 depressed-convex, occupying less than one-third the entire sur- 

 face of the head, limited. laterally by well-defined nearly straight 

 dorsal furrows, key-stone shaped in outline, widest in front, 

 the width at the occipital furrow being about three-fifths 

 that across the frontal lobe ; frontal lobe transversely sub-ellip- 

 tical in outline, a little elevated above the surface of the lateral 

 lobes, its length five-eighths its width, occupying nearly one- 

 half the entire glabella; first lateral lobes wedge-shaped in out- 

 line, twice as wide at the dorsal furrow as at their inner ex- 

 tremities; second lateral lobes quadrangular, smaller than the 

 first; third lateral lobes similar to the. second but slightly smaller; 

 externally all three lateral lobes on each side are confluent along 

 the dorsal furrows, but in the internal casts the lateral furrows 

 continue to the dorsal furrows ; the inner extremities of the first 

 lateral furrows are nearly opposite the anterior extremities 

 of the eyes, from their origin they are directed obliquely outward 

 and forward, they are most deeply impressed toward their 

 inner extremities; second lateral furrows nearly transverse 

 in direction, not continuous across the median portion of the 

 glabella and not confluent with the dorsal furrows; third pair 

 of lateral furrows similar in all respects to the second except 

 that they may be a little longer. Occipital furrow continuous 

 across the posterior margin of the glabella, joining the dorsal 

 furrows on either side, it is most strongly impressed at the 

 lateral extremities, becoming fainter across the median portion 

 of the glabella. Occipital segment with nearly parallel anterior 

 and posterior margins, its length a little greater than that of 

 either the second or third lateral glabellar lobes, and its width 

 a little greater than the glabella at its posterior margin. Cheeks 

 sub-triangular in outline with a broad flattened marginal border 

 which is continuous around the anterior margin of the glabella 

 with a flat rounded median extension in front. Anterior 

 limbs of the facial sutures parallel with the margin of the gla- 

 bella from the anterior extremities of the eyes towards the 

 anterior margin of the head, then continuing parallel with its 

 frontal margin completely around the anterior extremity of 

 the glabella, the sutures from the two sides being continuous; 

 the posterior limbs directed laterally from the posterior ex- 

 tremities of the eyes, describing a slightly sigmoidal curve 



