Palceozoir Fo^^ih. 395 



heads, with the margins unfortunately incomplete. It is dis- 

 tinguished easilj' from P. africanus by the more pointed glabella 

 and by the occipital furrow being continuous over the axis. 



Head triangular ; l)readth approximately 1^ times the length, 

 not counting the terminal spine, which is missing. Glabella 

 elongated, broadening in front, straight-sided, moderately raised 

 above the cheeks, and separated from these by the swelling rather 

 than by a definite furrow. The front pair of axial furrows direc- 

 ted obliquely forwards ; the second pair almost peri)endicular to 

 the axis and shallow : the third pair very deep, almost perpendicu- 

 lar to the axis, the axial ends turned inwai'ds and forwards. 

 Occipital furrow straight, fading out towards the margins of the 

 cheeks, very deep on either side of the axis, but still strongly 

 marked where it l^ends forwards to pass over the axis. Neck seg- 

 ment smooth. Cheeks curved evenly downwards, steep near the 

 front part, making the frontal lobe of the glabella prominent. 

 Suture runs inwards and downwards to the base of the eye, then 

 straight upwards and round the end of the glabella just above the 

 margin. Ey^s prominent with facets borne on an ui)right, out- 

 wardly directed surface. Palpebral lobe asymmetrical with 

 vision greatest in front : lower edge of eye a little in front of the 

 third axial furrow. Viewed from the side the glabella meets the 

 reflexed border in a rounded margin slanting upwards from below, 

 the cheeks forming wings which reach lower down than the 

 reflexed border of the cephalic shield. The apex is upturned and 

 probably bore a small spoon-shaped projection, as in Gryphaeus 

 giganteus, Ulrich, and G. cajfei\ Salter. Surface smooth, except 

 the frontal lobe of the glabella, which is irregularly granulated. 



Remarks. — The absence of any sign of a spine on the neck 

 segment separates this form from P. arhuteus^ Lake. It is not 

 represented in the Bain collection described by Salter. It is verj- 

 close to Phacops (Gryph(tf(i>i) gigantruft, Ulrich, from the Ida 

 shales of Chnaraui, Bolivia^. 



Dimensions : Length, l.(S. cm. Breadth, ."J.,'} cm. Width of 

 glabella at l)ase, 1.1 cm., in front, 1.4 cm. Le-ngth of ghihella from 



'Ulrich, A., Versteiiierungen aus Bolivien, Neues Jahrb. VIII., Beil 

 Bd., 1892, p. 4, PI. I., figs. 6-8, especially fig. 8. 



