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cave curve, on each side. Eyes small, placed very near the posterior margin 

 of the head and opposite the most contracted portion of each of the free 

 cheeks : ocular ridges moderately prominent, slightly curved and conver- 

 ging obliquely forward from the eyes to their terminations near the frontal 

 margin, where they are about twice as close together as at their commence- 

 ment anteriorly. Characters of the glabella unknown. Outer margin of 

 each of the free cheeks somfewhat expanded anteriorly and forming a not 

 very prominent rounded lobe, which is armed with eight very short pointed 

 spines — slightly contracted behind the midlength and terminating poste- 

 riorly in a straight and pointed genal spine, which is a little shorter than 

 that of the pleura of the first abdominal segment, and diverges outward 

 and backward at an angle of 40° to a line that might be drawn at a 

 right angle to the longitudinal axis. 



" Thorax arched upon the axis, depressed and flattened on the pleurae : 

 composed of nine segments : axis occupying more than one third of the 

 entire breadth without the s^jines, and narrowing very gradually to the 

 posterior end : its annulations horizontal, subparallel and nearly straight, 

 but faintly sinuous at their margins, both in front and behind. Pleurae 

 also decreasing very gradually in breadth to the posterior end of the thorax, 

 nearly straight and terminating externally on each sidcin a long and very 

 slender spine, which is bent backward and outward at an angle of about 

 57°. The spines increase gradually in length posteriorly, the two spines on 

 the anterior thoracic segment being shorter than the pleurae from which 

 they proceed, and nearly equal in length to the genal spines immediately in 

 front of them, whereas in the posterior thoracic segment the pleural spines 

 are nearly three times as long as the pleurae and as the spines on the pleurae 

 of the anterior thoracic segment. 



" Pygidium broad and short, its outer margin broadly rounded and 

 fringed with spines, its inner or anterior margin almost straight and nearly 

 three times as broad as the length of the non-spinose portion along the 

 median line ; its axis moderately convex and its pleurae flat. Axis nar- 

 rowly rounded posteriorly and terminating just within the margin of the 

 pygidium, apparently bearing two transverse annulations, the posterior 

 unarmed and the anterior bearing a long and very slender primary spine on 

 each of its rounded postero-lateral angles. These primary spines, whose 

 length considerably exceeds that of the united pygidium and thorax, di- 

 verge for the greater part of their length at an angle of about 48°, but 

 curve slightly inward at their outer ends. Outer margin of the pygidium 

 armed with four secondary internal spines between the two piimaries, and 

 with five secondary external spines on each side of the latter. The four 

 secondary internal spines are moderately close together, nearly equal in 

 length and about one fourth as long as the primaries. The five outer 



