NO. 3 UPPER CAMBRIAN TRILOBITE FAUNAS — RASETTI 87 



APHELASPIS BUTTSI (Kobayashi) 



Plate 16, figures 1-7 



Olenus cf. truncatus (Briinnich) Butts, 1926, pi. 9, figs. 6, 7. 

 Proaulacopleura buttsi Kobayashi, 1936, p. 93, pi. 15, fig. 6. 

 Proaulacoplenra buttsi Kobayashi, Resser, 1938a, p. 95, pi. 16, fig. 18. 

 Aphelaspis buttsi (Kobayashi) Palmer, 1962b, p. 35, pi. 4, figs. 23, 26, 31, 32; 

 pi. 6, fig. 15. 



Large numbers of specimens, many of them complete exoskeletons 

 like the holotype, are available from the type locality in Alabama. 

 This material is all flattened in shale, hence identification with lime- 

 stone specimens inevitably leaves some uncertainty. However, all the 

 features of cranidium, free cheek, and pygidium, excepting the con- 

 vexity that cannot be compared, match so perfectly that reference of 

 the Tennessee material to the species seems justified. Palmer (1962b) 

 referred to A. buttsi, his excellent limestone specimens from Nevada, 

 which are identical in all respects with those from the writer's collec- 

 tions. 



Occurrence. — The species is very abundant in collection cno/15, 

 Three Springs, from beds containing a mixture of genera of the Crepi- 

 cephalus and Aphelaspis zones. Cranidia of an Aphelaspis collected 

 from the essentially equivalent beds cno/14 at Russell Gap may belong 

 to the species, but they cannot be distinguished with certainty from 

 A. lata in the absence of associated pygidia. This is the oldest Aphe- 

 laspis species found in Tennessee. The type locality is U.S.N.M. 91o, 

 near Center, Ala. 



ry/)^.?.— Holotype : U.S.N.M. 93048. Plesiotypes: U.S.N.M. 

 144658. 



APHELASPIS LATA Rasetti, new species 



Plate 16, figures 8-20 



Available material. — Large numbers of cranidia and several free 

 cheeks and pygidia, both preserving the test and exfoliated. 



Description. — Cranidium proportionately wide and short, its sagit- 

 tal length equaling the width between the palpebral lobes, which is 

 slightly greater than the width between the anterior angles. Glabella 

 somewhat wider and shorter than in most species, of moderate con- 

 vexity. Fixed cheeks not rising above the level of the axial furrow. 

 Preglabellar field of moderate, uniform longitudinal convexity ; border 

 somewhat convex, defined by change in slope and shallow border 

 furrow. Length of frontal area 0.6 times the length of glabella; 

 sagittal length of border slightly less than half the length of pre- 

 glabellar field. Border furrow somewhat angular on midline. Pal- 

 pebral area horizontal to slightly downsloping, wider than in most 



