344 



Of very large size (over 130 mm.), slate grey in colour, 

 with two conspicuous white spots upon the upper side of 

 the anterior half of segments , side margins of the keels tri- 

 dentate or quadridentate, the pores widely separated from 

 this edge; sterna with two pairs of spinules. . . mirandus. 

 Of medium size (less than 100 mm.), chocolate brown in 

 colour, keels often flavous, with their margins less strongly 

 dentate and the pores closer to them. 

 a 5 . The distance between the pores and the lateral margin 

 greater than the diameter of the rim of the pore. 

 a e . Collum scarcely carinate and only a little wider than 

 the head ; tail with strongly convex border ; granula- 

 tion finer, margins of keels scarcely lobulate 



xanthopus. 



b G . Collum distinctly carinate, considerably wider than the 



head ; tail more squared ; granulation coarser, edges of 



the keels more clearly lobulate laticollis. 



b*. The distance between the pores and the edge less than 

 the diameter of the porous area. 



a 7 . The sternal areas armed with two pairs of spines, 



one spine at the base of each leg, tail oval. 



a 8 . Keels narrower at the base, not shouldered, those 



at the posterior end of the body produced behind 



into a long slender spiniform process; sternal spines 



small , tuberculiform ; granulation of terga finer . . 



monticola. 



b 8 . Keels broad at the base, shouldered, those at the 



posterior end much less acutely spiniform; sternal 



spines longer ; granulation of terga coarser 



subspinosus. 

 b 1 . Sternal areas unarmed, keels distinctly shouldered. 

 a 9 . Posterior keels with their posterior angles pro- 

 duced into a long spiniform process. 

 a 10 . Tail subquadrate, with long parallel sides and 

 lightly convex posterior border; granulation 



coarse humberti. 



b { °. Tail parabolic, with widely rounded posterior 

 border; granulation much finer . . flavisternus. 



