lO SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 97 



tract a, shows that V. idahoensis has the rear spines set wider apart, 

 giving the entire pygidium a wider aspect. V. idahoensis has incom- 

 pletely fused pleural furrows. 



Locality 37m. 



Cotypes. — U.S.N.M. no. 95042. 



SCHISTOMETOPUS, n. gen. 



Diagnosis. — Glabella long, occupying nearly the entire cranidial 

 length ; tapered slightly. There are four pairs of glabellar furrows and 

 the occipital furrow. Fixigenes about half width of glabella. Anterior 

 suture slightly divergent. Posterolateral limbs rather short. Eyes 

 small, situated slightly behind the midpoint. Eyelines curved back- 

 ward, arising opposite anterior pair of glabellar furrows. Brim con- 

 sists of rim only. Two deep furrows run forward from the anterior 

 angles of the dorsal furrow and separate a central thickened portion 

 from the two flat lateral portions of the rim. 



Genotype. — 5". typicalis, new species. 



Nanu\- — (TxtoTos = divided : /iero7ro?== forehead. 



SCHISTOMETOPUS TYPICALIS, n. sp. 



Plate I, fig. 12 



During preparation the important rim was injured because the speci- 

 men was thought to be an Elrathia. Fortunately, enough of the rim 

 remains to show its features. It will be observed that the glabella of 

 6". typicalis is like that of Elrathia sainpsoni because of the four sets 

 of furrows. 



Locality 37m. 



Holotype. — U.S.N.M. no. 95040. 



ZACANTHOIDES Walcott, 1888 

 ZACANTHOIDES SAMPSONI, n. sp. 



Plate I, figs. 27-30 



A small form of Zacanthoides is present in the Lake view limestone. 

 The pygidium has spines of nearly equal length, and the thorax has 8 

 or 9 segments. Glabellar furrows are short and shallow. 



Locality 37n. 



Holotype and paratypcs. — U.S.N.M. no. 95043. 



