TRILOBITA—OPISTHOPARIA. 



303 



XLVIII. Phillipsia Portlock. 



Like Proetiis but with a more prominent glabella, with strong 

 basal glabellar lobes (due to the strong fourth pair of lateral fur- 

 rows reaching the neck furrow), longer and more segmented 

 pygidium, and nine thoracic segments. Occipital lobes obsolete or 

 obsolescent. This genus replaces Proetus in the late Palaeozoic 

 horizons. Differs from Griffithides in the subparallel sides of the 

 glabella. 



The subgenus Brachymetopus McCoy has the glabella very short 

 and the pygidium generally granulose on the axial rings and pleura. 

 Devonic-Permic. 



124. P. (Brachymetopus) tuberculata Meek and Worthen. 



Mississippic. 



Pygidium very convex, nearly three fourths inch long and seven 



eighths inch wide; axis of pygidium of about 17 segments, each of 



which has six small tubercles, arranged so as to form six rows. 



Fig. 1 614. Cyphaspis ornata, frag- 

 ment of cephalon. (After Hall.) 



Fig. 1 61 5. Phillipsia {Brachyme- 

 toptis) lodiensis. (Pal. Ohio.) 



Pleura likewise ornamented by rows of tubercles. Margin flat 

 and prominent. 



Burlington of Illinois and Missouri. 



125. P. (Brachymetopus) immatura Herrick. Mississippic. 

 Very similar to P. tuberculata but much smaller. Pygidium 



marked with duplicate ribs anteriorly, which are slightly nodose at 

 their marginal ends. Axis and lateral lobes each with about three 

 large, distant tubercles. 



Burlington of Missouri; Waverly of Ohio. 



126. P. (Brachymetopus) lodiensis Meek. (Fig. 161 5.) 



Mississippic. 



