21 



Ckyptonymus vARiOLARis. Brong., 1822. 



Plate I, Fig. 6-10. Plate III, Fig. 13-14. 



The general form is obtusely ovate. Cephalic shield 

 obtuse, and not jiroduced into spines ; the posterior 

 angles are ornamented with a cluster of tubercles, which 

 occasionally terminate into a single tubercle. The gla- 

 bella is inflated and covered with large tubercles, equally 

 disposed. The thorax consists of 11 segments. The 

 pygidium is convex and triangular, its length and 

 breadth about equal ; and its axis has 9 to 10 rings, 

 much naATOwer than its lateral portions, and gradu- 

 ally diminishing into a blunt apex ; the 7 pleurse are 

 broad and abrujitly bent downwards and backwards. 



The posterior pleurae are rounded oif at their extrem- 

 ities and extended below the blunted axis. Each pleurae 

 has a tubercle near the axis. The upper ring of the 

 axis has usually a single large tubercle upon its centre, 

 the 2nd has a central puncture or slight depression be- 

 tween 2 large tubercles ; the remaining rings have al- 

 ternately a tubercle and a puncture between 2 tubercles, 

 except the 3 posterior rings, which have each a single 

 tubercle only. Variations : the front of the glabella is 

 more gibbous in some specimens than in others, and 

 the marking of the pygidium is not constant. 



Localities : Wenlock Limestone, Dudley, etc. 



Cryptonymus deltoideus. Shumard, 1855. 



Geological Survey of Missouri, P. 19S, Pl. B, Fig. 10. 



Pygidium subtriangular, width greater than the 

 length, moderately convex, arched before, posterior ex- 

 tremity rounded and bent slightly upwards. The axis 



