THE NATURAL HISTORY SURVEY. 235 



very convex, the anterior and lateral slopes protuberant, 

 Anterior, lateral furrows broad and deep, sub-parallel from the 

 frontal margin upward and backward, slightly converging pos- 

 teriorly where they terminate in a depression between the inner 

 extremities of the third lateral lobes. Second lateral furrows 

 obsolete. Third lateral furrows as strong as the anterior pair, 

 curving from the dorsal furrow slightly upward and backward, 

 meeting the anterior pair in the depression between the third 

 lateral lobes. Median lobe sub-ovate of sub-quadra.te in outline, 

 occupying more than one-third of the entire surface of the gla- 

 bella, broadest in front of the center where its width is from two- 

 thirds to three-fourths its length, strongly 'convex and protu- 

 berant beyond the frontal margin anteriorly, the posterior slope 

 gently convex and terminating in the depression between the 

 inner extremities of the third lateral lobes; at its most anterior 

 extension the median lobe bears "two large spines which are 

 produced forward in a nearly horizontal direction, slightly di- 

 verging from the base, on the dorsal surface in front of the 

 middle are two other similar spines nearly in line with those in 

 front, one of which is sometimes situated farther forward than 

 the other, they are directed obliquely upward.. and forward. 

 The compound anterior lateral lobes large, sub- triangular or 

 irregularly sub-ovate in outline, acutely angular behind, the 

 longer axis oblique to the median line of the cephalon, the 

 surface somewhat depressed between the median lobe and the 

 third lateral lobes. The third lateral lobes sub-elliptical or sub- 

 ovate in outline, more than half the size of the anterior lobes, 

 strongly convex, bearing a large spine on the outer extremity 

 above the eye-lobe. Occipital lobes small, nearly flat, more or 

 less indistinctly outlined, one-third or less than one-third the 

 size of the third lateral lobes. Occipital furrow broad and deep 

 in its central portion, dividing laterally, one division passing 

 in front and the other behind the small occipital lobes, the 

 divisions much narrower than the central portion. In front of 

 the occipital furrow, between the inner extremities of the third 

 lateral lobes, is a rather broad depression across which an in- 

 distinct ridge connects the inner extremities of these lobes. 

 This ridge is surmounted by three tubercles, one situated me- 

 dially and one at each end. Occipital segment strongly arched, 

 broad, elevated along the posterior border which is produced 

 into three strong spines directed obliquely backward and upward, 

 its surface sloping toward the front. Fixed cheeks convex, 

 narrow in front, becoming much broader posteriorly, with small 



