NO. 3 CAMBRIAN TRILOBITES I7I 



NORWOODIA PONDEROSA, new species 

 Plate 28, ngs. i, la-b 



This species is represented by a number of cranidia and associated 

 pygidia. It differs from both A'', simplex and N. saffordi (pi. 27) 

 by its much larger genal spines and the narrow, strong frontal limb 

 that appears to be without a defined frontal border. There are 

 slight traces of two pairs of glabellar furrows and a faint defined 

 occipital ring which has a short median spine with a strong base. 

 Outer surface unknown. 



Formation and locality. — Upper Cambrian: (90a) Conasauga 

 shales ; Cedar Bluff, Cherokee County, Alabama. 



NORWOODIA SAFFORDI, new species 



Plate 27, figs. I, la-f 



This species differs from Norzvoodia gracilis in the form of the 

 frontal limb and border, fixed cheeks, and genal spines, and in having 

 eight instead of nine thoracic segments. 



The outer surface of the test appears to have been rather strongly 

 granulated, as shown in the matrix of the species illustrated by figure 

 id, plate 27. 



Formation and locality. — Upper Cambrian: (103, 103a) Noli- 

 chucky shale. Second shale south of the ridge of sandstone " Town 

 Knobs " on the road from Rogersville to Dodson Ford, Hawkins 

 County; and (107a, 107b) shales in railroad cut in Bull Run Ridge, 

 northeast of Copper Ridge, 11 miles (17.6 km.) northwest of Knox- 

 ville, Knox County, both in Tennessee. 



NORWOODIA SIMPLEX, new species 



Plate 27, figs. 3, 3a-b 



This species differs in its cranidium, genal spines, and number of 

 thoracic segments from A\ gracilis; it has also a rounded appearance 

 not seen in other species. The number of thoracic segments is eight, 

 which is the same as in A'^. saffordi. The pygidium is nearly smooth, 

 the furrows on the axial and pleural lobes being little more than 

 incised lines. 



Surface apparently finely granulated. 



One entire dorsal shield has a length of 10 mm. 



Formation and locality. — Upper Cambrian: (90a, 91) Conasauga 

 shale; Cedar Bluff; also (145) bluffs of Coosa River, east of 



