320 Frederick Cliapriiaii : 



ring narrow, neck-furrow deeply impressed. Fixed cheeks 

 moderately broad, subtriangular, and deeply incised at junction 

 witli the glabella ; outer margin gently sloping outward pos- 

 teriorly, and with a semilunar depression on the ocular margin. 

 Surface finely tuberculat«. 



Pygidium broad, subtjuadrate, rather depressed ; with the 

 posterior border slightly produced and rounded. Axial lobe 

 broad, and rounded on the upper surface, excepting at the 

 teruiinal which has the upper surface slightly cupped ; axis 

 more than three-fourths the length of the pygidium, thus differ- 

 ing from that in Dii/eJoccphahis, divided into five segments, 

 all of which, except the posterior, are narrow ; axial sutures 

 wide, moderately impressed, and widely curved to almost 

 straight ; furrows of the lateral lobes at first gently sloping pos- 

 teriorly, and then curving sharply backwards. Margin with a 

 doublure, and remnants of two [1) long, divergent spines, 

 directed backwards and outwards. 



Dimensions. — 



Cranidiuin — Length from base of neck ring to anterior 

 border, 4.5 mm. Apjiroxiuuxte width of cranidium, 8.5 mm. 

 Lenofth of frlabella, 3.5 mm. 



Pygidium. — Greatest width, 12 mm. Approximate length 

 of present specimen, measured over the middle vertical line, 

 8 mm. Greatest width of axial lobe, 3.5 mm. 



A free cheek (PI. LVTII., Fig. 4) is al.so firovisionally referred to 

 this species. It is wide, more subtrigonal in shape than those of 

 Ptychoparia here previously desci'ibed, finely tuberculate and 

 radiately wrinkled; anterior margin nearly straight for half the 

 distance to the genal angle, then roundly curved to meet the long 

 slender, outwardly curved genal spine ; external border of free 

 cheek with a narrow rounded margin as far as the genal angle, 

 where it aiierges into the genal spine. 



The dimensions of this free cheek are as follows : — ^Anterior 

 extremity to genal angle, 5.5 mm. : length of spine. 4.75 mm. ; 

 greatest width of free cheek, about 3 mm. 



Ohservations. — Fragmentary examples of what are here re- 

 garded as the cranidia of f 'repieejjhalus etheridgei (typified 

 by the pygidium) are not uncommon in the Dolodrook Lime- 

 stone. They show the same supei-ficial characters of a finely 



