98 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. IO3 



Additional specimens of this species are figured to illustrate char- 

 acteristics of pygidium and the peculiar flatness of the head. 



Honey Creek limestone; (loc. I2p) 4 miles southeast of Hennepin, 

 and other localities in the Arbuckle Mountains, Oklahoma. 



Cotypes. — U.S.N.M. Nos. 93025a, b; plesiotypes, Nos. 108818a, b, 

 108820a, b. 



ELVINIA VAGANS, new species 

 Plate 19, Figures 6-9 



Cranidium, exclusive of posterolateral limbs, nearly quadrate. Gla- 

 bella, tapered to a slightly rounded frontal outline, is a little more 

 than two-thirds the glabellar length. Brim divided about equally 

 between a well-defined, slightly upturned rim, and preglabellar area. 

 At their narrowest point the fixigenes are about one-third the glabellar 

 width. Anterior to the eyes the facial suture diverges moderately to 

 form rather square anterior angles. Posterolateral limbs long and 

 stout. The moderately bowed eyes are a little less than one-third the 

 cranidial length and are set nearly parallel to the lateral dorsal furrow. 

 Occipital furrow deep both on glabella and posterolateral limbs. Rear 

 glabellar furrow shallow, others not developed. Laterally the glabella 

 stands above the fixigenes with gentle curvature. Fixigenes nearly 

 flat. Longitudinally the head has considerable convexity attained by 

 an angulation near the midpoint. Each half individually is nearly in 

 a plane, except for the furrows and raised rim. Associate pygidium 

 normal in all respects. The wide axis reaches nearly to the rim. Three 

 axial furrows are well developed. The nearly flat pleural platforms 

 have two wide shallow furrows and a thickened and raised border. 



Honey Creek limestone; (loc. 9q) 15 miles northwest of Fort Sill, 

 Wichita Mountains, Oklahoma. 



Holotype. — U.S.N.AL No. 108821a; paratype. No. 108821b. 



ELVINIA BREVIFRONS, new species 

 Plate 19, Figures 10-14 



This species is so constricted in brim width and length that it is no 

 longer fully characteristic of Elvinia. Cranidium as a whole forms a 

 truncated isosceles triangle. The long glabella which tapers to a 

 truncated front, with slightly rounded anterior angles, is demarcated 

 by a shallow dorsal furrow. Brim width equals about one-fourth the 

 glabellar length and has a nearly straight front outline. The occipital 

 and rear glabellar furrows are deep. Measured at the same point the 

 fixigenes are about half the width of the glabella. In front of the 



