26 



by a strong sulcus from the neck segment, -wliicli Is 

 broad and prominent. It is indented half-way up by 

 three short furrows on each side. The cheeks, though 

 convex, are much less so than the glabella, and they bear 

 the eyes in the middle of the cheek. * * The outer 

 margin of the cheek is thick, and separated by a fur- 

 row, and the posterior. angles are produced into spines ; 

 the posterior edge also has the strong neck furrow con- 

 tinued along it. The glabella is covered with tubercles 

 of unequal size, mixed with granules, but the specimen 

 does not show whether these tubercles have each a pit 

 on their summit. * * The thorax consists of 11 seg- 

 ments ; the axis moderately convex, of nearly equal 

 breadth throughout, and considerably narrower than 

 the pleura. These are quite horizontal as far as the ful- 

 crum, which is placed more than half-wa}' from the axis ; 

 and from this point they curve backward and downward 

 to the tip, which is again a little bent forward, so that 

 the line from the fulcrum outwards is a sigmoid curve ; 

 the hinder pleurse curve less backward. Each jileurje 

 is nearly semicylindrical, with three or four tubercles 

 along it. * * 



Tail of a triangular form, wider by one third than 

 the length, with an obtuse rounded apex, and flattened 

 above, the sides and the tip deflected, so that the tail is 

 moderately convex ; the axis at the upj)er part is about 

 one fourth the width of the tail, and tapers to a point 

 at some little distance within the blunt apex ; it is con- 

 vex at its broadest end, and there the rings are contin- 

 uous across, but from about the upper third it becomes 

 flatter, and the rings are efikced along the middle ; its 



