NO. 3 UPPER CAMBRIAN TRILOBITE FAUNAS — RASETTI 43 



area about one-fourth the glabellar length, slightly convex, barely 

 divided by a trace of a border furrow ; anterior outline somewhat 

 pointed medially. Ocular ridges faint ; palpebral area about one-fourth 

 the glabellar width ; palpebral lobes very small, at level of anterior third 

 of glabella. Anterior section of facial suture convergent immediately in 

 front of palpebral lobes; posterior section slightly convex outward, 

 gradually curving backward and inward to produce broad, well- 

 rounded posterior area. Furrow on posterior area broad and shallow. 

 Free cheek rounded at genal angle; border narrow but fairly distinct 

 anteriorly, becoming indistinct posteriorly. Surface of test smooth. 

 Length of largest cranidium 2.4 mm. 



Discussion. — The pygidium has not been identified. The cranidium 

 of G. declivis differs from other species of the genus in the steeply 

 downsloping palpebral area and the tendency to obsolescence of all the 

 furrows ; however, its close relationship to the more typical forms is un- 

 mistakable. 



Occurrence. — The type is from Oder's collection No. 2, Hurricane 

 Hollow. Also present in collections cnr/15. Three Springs, and cnr/16. 

 Smith Hollow. In all these occurrences it is associated with Aphelaspis 

 walcotti. Rare specimens were collected at locality cnqV20, Washburn, 

 in somewhat higher beds. 



Types.— RoXoty^e: U.S.N.M. 144556. Paratypes: U.S.N.M. 144- 

 557. 



Genus AMIASPIS Lochman, 1944 



Type species. — Amiaspis erratica Lochman. 



AMIASPIS ERRATICA Lochman 



Plate 5, figure 20 



Amiaspis erratica Lochman, in Lochman and Duncan, 1944, p. 68, pi. 8, figs. 

 41-46. 



A few cranidia do not appear to differ appreciably from topotype 

 material from Montana. 



Occurrence. — Locality cnn/ 16, Smith Hollow. 

 7y/>^.—Plesiotype: U.S.N.M. 144558. 



AMIASPIS OBSOLESCENS Rasetti, new species 



Plate 5, figures 21-24 



Available material. — The holotype, a good cranidium, is the only 

 specimen from the type locality. Several fragmentary cranidia from 

 another locality are also available. 



Description. — Glabella large, somewhat tapered, widely rounded in 

 front, unfurrowed, barely defined on the outer surface by a very shallow 



