8 F. R. Coicper Reed — Undescrihed Trilohites. 



junction of the head and thorax, forcing back the head over the 

 first few segments of the body and concealing them. In the Fletcher 

 specimen there are indications of one segment being thus covered, 

 making the actual number of thoracic rings to be ten. 



Axis of thorax gently convex, broad, tapering gradually to the 

 pygidium, each ring consisting of a simple narrow band, apparently 

 devoid of ornamentation. The anterior rings of the axis appear to 

 be wider than the corresponding pleurae, but the posterior ones to be 

 narrower. Axal furrows weak. 



Pleurge semicylindrical, horizontally extended as far as the 

 fulcrum, but then bent downwards, flattening again towards their 

 extremities, which are separate and free. The fulcrum is distant 

 from the axal furrow about one-third of the length of the pleura, 

 and is obtusely rounded. Each pleura curves gently forwards to 

 the fulcrum, then bends more strongly backwards, and again bends 

 forward slightly towards its extremity. The surface of each pleura 

 is marked along its inner portion by a nearly median furrow, which 

 runs straight outwards to the fulcrum and then curves backwards 

 over the outer portion to the point, dividing this outer portion into 

 a flattened anterior and an elevated posterior part, but near the end 

 the whole breadth of the pleura is flattened. The extremity is 

 bluntly pointed. There are a few obscure traces of tubercles on the 

 pleurae. 



Pygidium.- — Broad and roughly pentagonal, gently convex from 

 side to side, having its lateral lobes bent down, but flattened along 

 its margin. Its component segments are closely fused together, and 

 only the two anterior pleuraa on each side are marked out. 



The pygidium is arched forwards in front ; posteriorly it is 

 forked, and each side is angulated by the projection of the extremities 

 of the second pair of pleurte. 



The posterior margin lying in the fork is rather less than half the 

 anterior width of the pygidium. The re-entrant angle is about 135°, 

 and the sides meet the lateral borders at an angle of a little over 

 90° at the obtusely rounded divergent points of the fork. (In the 

 Fletcher specimen these points are rather more acute.) 



Axis cylindrical, convex, and prominent, being strongly raised 

 above the lateral lobes. Its posterior end is pointed and prolonged 

 to reach the posterior margin of the pygidium at the re-entrant 

 angle, sloping down rapidly to the level of the flattened border. 

 The cylindrical portion of the axis measures only about two-thirds 

 the total length of the pygidium. 



First axial ring only distinct, and marked oflf behind by a strong- 

 continuous furrow. Very obscure traces of four or five rings behind 

 it. Axal furrows well marked on each side of the cylindrical portion, 

 but very faint behind it and scarcely traceable to the margin. 



Lateral lobes of pygidium, bent down on each side of the axis and 

 consisting of a convex inner portion and a flattened marginal portion. 

 Each lateral lobe measures anteriorly about 1\ times the width of 

 the axis. 



First pair of pleuraj distinct, each pleura expanding. outwardly to 



