66 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. IO3 



reduced, consisting only of a slightly elevated portion of the fixigenes. 

 The eye band is turned up but does not have a distinct palpebral 

 furrow, 



St. Charles limestone; (loc. 66z) 5 miles west of St. Charles, Bear 

 River Range, Idaho. 



Holotype.—U.S.'N.M. No. 108749. 



ELLIPSOCEPHALOIDES BUTLERI, new species 

 Plate ii, Figures 14, 15 • 



This species, represented by numerous cranidia, is preserved in 

 sandstone, and is associated with Briscoia. It has a typical develop- 

 ment for the genus but is not proportionally as wide as the genotype. 

 Glabellar furrows are present but may be lacking on the test. The 

 eyes are strongly bowed and situated about the middle of the 

 cranidium. 



Sawatch formation; (loc. 37x) near Oilman, Mosquito Range, 

 Colorado. 



Holotypc.—U.S.'NM. No. 108751a; paratype. No. 108751b. 



ELLIPSOCEPHALOIDES NITELA, new species 



Plate it, Figure 13; Plate 12, Figures 1-3 



This narrow form, represented by many examples, most resembles 

 E. silvestris. Compared with that species E. nitela is somewhat 

 broader and in the pygidium the pleura are wider. The nearly quad- 

 rate glabella has rounded anterior angles. The fixigenes are less than 

 half the glabellar width, and are a little wider than the brim. The 

 eye lines are weak and the broad eye bands are clearly defined by the 

 palpebral furrows. The simple brim has a slight elevation in the 

 middle. The associated pygidium has a broad axis on which the fur- 

 rows are deep. In cross section the axis stands above the pleural 

 lobes, which retain both the pleural grooves and furrows. The latter 

 bisect the pleura obliquely, decreasing in strength posteriorly. Four 

 marginal spines, decreasing in size from front to back, terminate the 

 four pleural segments. 



Honey Creek limestone; (loc. 12m) 7 miles north of Springer, 

 Arbuckle Mountains, Oklahoma. 



Holotype. — U.S.N.M. No. 108750a; paratypes, Nos. io875ob-d. 



ELLIPSOCEPHALOIDES MONSENSIS, new species 

 Plate 12, Figures 4-6 



This narrow species similar to E. moutis is represented by a num- 

 ber of cranidia and the pygidiuuL The quadrangular glabella is about 



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