432 MR. F. R. COWPER REED ON" THE [Aug. 1 896, 



The lateral portions of the pygidium are flat and horizontally 

 extended in one plane. All the furrows are of equal strength. The 

 anterior pair of pleurae is very imperfectly preserved; only the 

 base is visible, but this part is seen to be equal in width to the first 

 two axal rings. The diagonal furrow across its surface starts from 

 nearly the middle of the base. From comparison with allied forms 

 it is probable that this first pleura ended on the margin in a short, 

 backwardly-directed, free point. 



The second pleura has the same basal width as the first, but its 

 posterior limiting-furrow starts behind the faint posterior limiting- 

 furrow of the third axal ring. This pleura expands in width in 

 the middle, and then contracts to end in a very short recurved point 

 which scarcely projects bejond the margin. The posterior limiting- 

 furrow of this pleura runs in a straight line to the pygidial margin 

 at an angle of about 45° to the median line of the axis. The 

 furrow traversing the surface of this pleura starts from the anterior 

 angle of the base and runs parallel to the posterior edge of the 

 pleura, but bends round sharply at its outer end to reach the 

 recurved point. 



The third pleura is almost a right-angled triangle, the hypotenuse 

 being the posterior or rather inner limiting-furrow, which is a 

 continuation of the axal furrow. The free terminations of this 

 third pair of pleurae form the short approximate points of the 

 posterior end of the pygidium, which give it its forked appearance. 

 The surface of each pleura of this pair is crossed by a furrow which, 

 starting from about the middle point of the base, runs backward 

 nearly parallel to its fellow and to the median line of the axis, but 

 with a very slight outward curvature. After traversing more than 

 three- fourths of the pleura it becomes faint, and curves round 

 rapidly inward to join the posterior limiting-furrow, thus circum- 

 scribing with the latter a lanceolate area, as in L. laxatus and 

 others. 



The axal furrows are distinct, and are continued directly into the 

 posterior limiting-furrows of the third pair of pleurae. These latter 

 furrows are straight, and converge posteriorly at an angle of 20° for 

 more than three-fourths of their length — i. e. to the point where the 

 diagonal furrow of the third pleurae joins them. Behind this point 

 they become fainter and converge twice as rapidly as before to meet 

 each other at the fork between the free ends of the last pair of 

 pleurae. The flat post-axal area between them has therefore a 

 tapering and peculiar shape. 



The whole surface of the pygidium is covered with tubercles of 

 medium size, with smaller ones interspersed. 



Measurements. 



millim. 



Length of pygidium 90 



„ axis 40 



Width of do. at front end 4'5 



