142 SIXTEENTH REPORT ON THE CABINET OF NAT. HISTORY. 

 DIKELOCEPHALUS PEPINENSIS. 



PLATE IX, FIGS. 1-4; AND PLATE X, FIGS. 13 - 17. 



Dikelocephalus pepinensis : Owen, Geol. Report of "Wisconsin, Iowa and Minnesota, page 



674, Tab. 1, f . 9 & 9 a; and Tab. 1 A, f. 7? 



Body comparatively narrow, subelliptical, wider anteriorly. General 

 contour of the head semielliptical, with extremely elongated 

 cheek-spines. 



Glabella prominent, longer than wide, usually a little narrowed 

 anteriorly. Occipital furrow straight and narrow : occipital ring 

 broad, depressed-convex, not rising higher than the glabella in 

 front of it. Posterior glabellar furrow a little oblique at the ex- 

 tremities, and straight in the middle : anterior to this furrow are 

 two slight indentations on each side of the glabella, near the 

 anterior limit of the palpebral lobe, which do not reach to its 

 summit. Dorsal furrow strongly defined, and joining a wider 

 furrow which limits the front of the glabella. 



Fixed cheeks narrow, expanded in the direction of the eye, and 

 separated by a distinct groove from the palpebral lobe; posterior 

 limb narrow, with the furrow extending about half its length, 

 and running out on the upper side : frontal limb convex, a little 

 wider in the middle than at the sides, separated from the glabella 

 by a wide slightly curving furrow. 



Movable cheek subtriangular, with a wide deep ocular sinus at the 

 inner angle, convex towards the eye, with a wide shallow depres- 

 sion just within a broad elevated limb; posterior margin short, 

 the genal angle produced in a long nearly straight spine, which 

 is more than twice as long as the body of the cheek. 



Hypostoma subelliptical, with a slight angular extension on each 

 side a little behind the centre; border elevated along the sides, 

 and slightly truncate in front : an oblique depression on each 

 side near the anterior end, directed from the margin forward and 

 towards the middle. 



Axis of the thorax convex and strongly defined : lateral lobes wider 

 than the axis, except at the posterior part, where they are nearly 

 equal. 



Pygidium somewhat semielliptical, wider than long, rounded in 

 front : axis strong and highly elevated, conical, tapering some- 

 what rapidly, marked by five annulations besides the elongated 

 posterior one and the anterior articulating segment. Lateral lobes 

 convex near the axis, and at the middle of their width sloping 

 abruptly downwards, with a flattened continuous margin; marked 



