321 



AMPHION WESTONI. (N. sp.) 



Fig. 307. 



Fig. 307. Amphion Westoni. a, the glabella with part of the cheeks (the specimen 

 is a cast of the interior, and does not shew the eye) ; 6, pygidium found associated 

 with it. 



Description. Glabella oblong, pentagonal, depressed convex, most 

 elevated along the middle ; sides straight and usually parallel, sometimes 

 slirhtly converging forwards ; anterior margin of glabella rounded angular 

 in the middle, then straight or gently convex to the anterior corners 

 which are rounded. Neck furrow extending all across. Three pairs of 

 glabellar furrows ; the second pair a little in advance of the mid-length ; 

 the first pair half way between the second and the neck furrow ; the third 

 pair running out just in advance of the anterior corners, sloping inwards 

 at an angle of 45 to the longitudinal axis. The furrows all extend in- 

 wards about one-fourth the width of the glabella. In most of the specimens 

 there is a small pit in the middle of the front margin. Sometimes the 

 first pair of furrows curve backwards and partially isolate the posterior 

 pair of glabellar lobes. The glabella is well separated from the cheeks 

 by deep dorsal furrows. The position of the eye has not been distinctly 

 made out, but it appears to be opposite the posterior glabellar furrow. 

 Length of largest glabella collected 10 lines ; width of the same 7 lines. 



The pygidium above figured, although widely different from that of 

 an ordinary Amphion in aspect, still exhibits, in its structure some affinity 

 thereto. It is triangular, tapering uniformly backwards with gently 

 convex sides to the apex which is pointed or very narrowly rounded. 

 Axis cylindro-conical, about one-third the whole width, strongly elevated 

 and sub-angular along the median line, becoming more depressed towards 

 the apex where it is scarcely raised above the general surface ; about 

 eighteen rounded ribs, those towards the apex sometimes obscurely de- 

 veloped. In the side lobes there are about ten ribs. Of these, the last 

 four or five are very imperfectly developed, and are nearly parallel with 

 the axis. On a side view this pygidium is very strongly convex, the ribs 



