LOWER HELDERBERG ROCKS. 365 



lateral furrow passes inwardly from the anterior margin to the narrower 

 part of the median lobe, whence, for a short distance, it is nearly 

 parallel to the axis, and then diverges abruptly towards the occipital 

 furrow. The median furrow is essentially parallel to the anterior lateral 

 one ; leaving the anterior lateral lobe with parallel sides, a moderately 

 arched outline, and having a length about three times as great as the 

 width. The occipital furrow is a well-defined semicircular groove, 

 showing a transversely oblong slightly elevated tubercle just behind 

 the posterior lateral lobe. The occipital annulation is twice as broad 

 as the furrow, and moderately convex. The entire head is covered by 

 small rounded pustules of unequal size. 



A separate hypostoma, found in the same strata and presumed to belong 

 to this species, has a width about one-fourth greater than the length ; 

 the central portion very broadly ovate, and its margin deeply indented 

 below the middle by two oblique sharply impressed furrows, the ante- 

 rior portion being transversely oval. The lateral borders are broad, and 

 the buccal border deeply notched. The surface of the anterior portion 

 is finely pustulose. 



A fragment of a pygidium, found in the same beds, preserves one side 

 with a portion of the axis. The axis, in its upper part, is abruptly 

 elevated, but its comparative height cannot be determined. The ribs 

 are bread, and distinctly grooved longitudinally a little in advance of 

 the centre. As far as can be ascertained, the axis is contracted a little 

 in advance of the middle of its length and expands again below, the 

 extremity being probably bifurcate. The surface is pustulose, a single 

 row of larger pustules marking centrally each lobe of the ribs. 



Fig. 1. Profile view of an imperfect head. The median lobe of the glabella is not represented 

 as su-fficiently prominent. 



Fig. 2. View of the upper side. 



Fig. 3. Anterior view, showing the elevation of the median lobe and the frontal limb. The 

 surface is represented as too coarsely pustulose. 



Fi<». 4. View of the upper side of tlie head. The median lobe of the glabella is sot sufficient- 

 ly narrowed in its posterior part. The surface markings in this figure present the 

 prevailing feature. 



Fi". 5. The median and anterior lateral lobes of the glabella of a larger specimen, which is 

 somewhat depressed. 



