?>5() AXNALS OV THE CaRXEGIE MuSEUM. 



correspond exactly to Whitfield's figures, and, in this locality, they 

 are associated with glabella which correspond with Billings' descrip- 

 tion of /.. uiinganensis. 



DeSCRII'IIOX. 



Cephalou. — Only the glabella and fixed cheeks are known, the free 

 cheeks and eyes not having, as yet, been found. Whole head quite 

 convex, sharply deflected in front. Median lobe nearly rectangular 

 posteriorly, but expanding rapidly in front. Neck ring nearly flat, 

 quite broad back of the middle lobe, but becoming narrower at the 

 sides. Along the anterior edge is a flat border which is very narrow 

 in front of the middle lobe but becomes wider in front of the side 

 lobes. The entire surface is covered with variously sized pustules. 



Thorax. — Unknown. 



Pygidium broad and flat, with strongly elevated axial lobe, which 

 is broad at the anterior end, tapers slightly for a short distance, and is 

 then reduced rapidly to a point. The axis always shows two strong 

 annulations and sometimes two faint ones. There are three broad 

 lobes on each side of the axis. They are directed backward and have 

 free terminations. Each lobe has a deeply impressed line which ex- 

 tends back about half its length. These lines are not very con- 

 si)icuous on the two posterior lobes. Surface entirely covered with 

 small pustules. 



The principal variations in the cephalons of this species lie in the 

 width of the middle lobe, which is narrow on some forms and wide 

 on others, and in the size of the pustules on the surface. On some 

 specimens the pustules are fine, even, and inconspicuous, while on 

 others there are large and small ones, making a pretty and showy 

 ornamentation. 



The pygidia vary in the number of annulations on the axis, and in 

 the width and convexity of the axis, relative to the rest of the pygid- 

 ium. In some, the cross section of the axis would be about semi- 

 circular. Others are more flattened and diminish more abruptly pos- 

 teriorly. 



Hyposioma. — The hypostoma found constantly associated with this 

 species is shown on plate 14, figure 3. 



Measitrcincnts. — A cranidium : 20 mm. long; 26 mm. wide. 



Middle lobe 7 mm. wide behind ; 15.5 mm. wide in front. Second 

 lobes, 7 mm. wide. 



