244 F. R. Coioper Reed — On Phacojjs (Chasmops) Marri. 



axis as far as the fulcrum, but at tliis point it bends backwards at an 

 angle of from 30° to 40° to its previous direction, and curves gently 

 downwards to its free end, which is blunt, rounded, somewhat 

 flattened and expanded. A deep furrow traverses each pleura 

 obliquely from the inner anterior angle towards the middle of the 

 free end, before reaching which, however, it dies out. 



Where the crust has been preserved a few tubercles and granules 

 are seen to occur on the axis and pleurae, but they are not so large 

 or so numerous as on the head. 



Summary of the normal characters of this form (undistorted). 



Head-shield semicircular, with an obtuse point in front. Posterior 

 margin forms a concave-backward curve to the large spines at the 

 angles. 



Glabella much dilated in front,' moderately inflated; base measures 

 about a quarter the width of head-shield, but only one-third the 

 greatest breadth of glabella which .is across transverse fi'ontal lobe. 

 The sides converge posteriorly at an angle of about 60°. Frontal 

 lobe transverse, twice as wide as long ; anterior border a gentle 

 convex- forward curve ; lateral angles rounded-truncate overhanging 

 the eyes ; a y-shaped series of puncta present on anterior portion 

 of this lobe. First side lobes ("cat's ear" lobes) extend from 

 neck-furrow to a point in front of eyes, i.e. for two-thirds the side 

 of the glabella; are triangular; inner angle about 90°; reach nearly 

 one-third across the glabella; anterior bounding furrow sinuous; 

 posterior furrow straight. Second or middle lobes very faint, 

 subcircular ; third or basal lobes rather more definite and wider. 

 Both second and third pairs of lobes completely embraced laterally 

 by first lobes. Axial furrows of glabella deep, narrow, straight as 

 far as anterior end of first lobe, then widen and curve outwards to 

 join marginal furrow. 



Neck-segment rounded ; neck-furrow deep, dies out before reach- 

 ing marginal furrow. 



Cheeks triangular, slightly inflated, highest along inner border. 



Genal angles terminated by large flat spines, broad at base, 

 slightly grooved, closely pressed against body-rings, extending to 

 8th or 9th thoracic segment. 



Marginal furrow narrow, smooth, and rounded, with smooth, wide, 

 slightly convex border external to it and forming edge of head- 

 shield. Anterior portion of border overhung to the extent of three- 

 fourths of its width by frontal lobe of glabella. 



Eyes large lunate, near inner margin of cheeks ; extend nearly 

 two-thirds the length of the first side lobe of the glabella; outer 

 side of base of eyes surrounded by deep crescentic channel. 



Cheeks and glabella finely granulated and covered with small 

 round tubercles, especially conspicuous on posterior part of glabella. 



Facial suture supra-marginal ; below eye it makes a convex- 

 forward curve and ends on outer margin at about the level of 

 the posterior end of the eye. 



