October, 1913. New Trilobites — Slocom 71 



well in front of the genal angles; eyes small. Thorax usually with 

 eleven segments, rarely nine to thirteen; axis prominent, narrower than 

 the pleura, bounded by strong axial furrows. Pygidium small, pleural 

 segments produced into points or spines." (Weller, Pal. Chicago Area, 

 p. 263.) 



Ceraurus pleurexanthemus Green. 



1832. C. pleurexanthemus Green, No. Amer. Jour. Geol., Vol. I, p. 

 560, pi. 14, fig. 10. 



1847. C- pleurexanthemus Hall, Pal. N. Y., Vol. I, p. 242, pis. 65-66. 



1847. C. pleurexanthemus S. A. Miller, Cin. Quar. Jour. Sci., Vol. I, 

 p. 132. 



This species is said to occur in Fayette County, but so far has not 

 been observed by the writer. A specimen in the collection of the 

 University of Iowa appears to belong to this species. It is said to come 

 from the Maquoketa beds of an adjoining county, but the exact data 

 are missing. 



Ceraurus milleranus Miller and Gurley. Plate XVII, Figs. 1-3. 



1894. C. milleranus Miller and Gurley, Bull. Ill, 111. St. Mus. Nat. 

 Hist., p. 80, pi. 8, fig. 10. 



Type specimen No. 6062 University of Chicago. 



General outline of the carapace, exclusive of the spines, subovate, 

 abruptly narrowed posteriorly; moderately convex, trilobation distinct. 



Cephalon semielliptical, width nearly three times the length; dorsal 

 furrows well marked. Glabella convex, narrower than the cheeks at 

 the occipital ring, gradually widening anteriorly until its width about 

 equals its length, abruptly bent downward at the frontal margin; 

 anterior lobe constituting about one-third the length of the glabella; the 

 three pairs of lateral furrows are short and about equidistant, forming 

 three pairs of small convex lateral lobes; the two anterior pairs of fur- 

 rows extend slightly forward, but the posterior pair is transverse for a 

 part of its course and then bends abruptly backward until it meets the 

 occipital furrow isolating the posterior lateral lobes. Occipital seg- 

 ment arched upward, higher than the anterior portion of the glabella, 

 greatest height at the posterior margin, sloping gradually into the 

 occipital furrow. This furrow is narrow and deep behind the posterior 

 lateral glabella lobes but wider and shallow in its median portion. 

 Cheeks convex with well-defined rounded marginal borders, posterior 

 angle produced into spines, which point backward; eyes prominent, 

 globular, placed near the center of the cheeks; the palpebral lobes bear 

 a pit near the base on the side nearest to the dorsal furrows; the facial 



