NO. 3 UPPER CAMBRIAN TRILOBITE FAUNAS RASETTI 51 



preserving the test. Blountia alethes was described on a cranidium of 

 Coosia illegitimately combined with an exfoliated pygidium of the pre- 

 ceding species. Since Walcott designated the cranidium as the holotype, 

 the name alethes belongs to the species of Coosia, as used by Resser. 

 The present generic assignment seems the proper one for Blountia 

 amage. This species was found to be exceedingly common at one local- 

 ity, and the numerous and better preserved material allows a more 

 complete description. 



Description. — Glabella defined by a fairly deep axial furrow, strongly 

 tapered, rounded in front ; glabellar furrows obsolete on outer surface, 

 faint on impression of interior. Occipital furrow wide, occipital ring 

 simple. Frontal area as in type species except for the greater distinct- 

 ness of the border furrow and border. Palpebral area approximately 

 horizontal, about 0.4 times the glabellar width ; palpebral lobes about 

 0.4 times the glabellar length. Posterior area somewhat more slender 

 and more deeply furrowed than in type species. 



Pygidium 1.4 times as wide as long. Axis elevated, slightly tapered, 

 occupying 0.8 of the pygidial length, extended into a brief postaxial 

 ridge, with about 5 distinct rings and a terminal section. Pleural lobes 

 convex, downsloping to moderately wide concave border. Anterior 

 marginal furrow deep and wide, three other pairs of furrows shallow 

 even on interior casts, traces of interpleural furrows also visible; all 

 furrows end sharply at a line that corresponds to the inner edge of the 

 doublure on the ventral side. The lateral and posterior margin with 

 almost even curvature, except for a slight indication of flattening 

 medially. Surface of test smooth. Length of largest cranidium 14 mm., 

 of largest pygidium 10 mm. 



Occurrence. — The type locality is U.S.N.M. 107, 11 miles NW. of 

 Knoxville. Type locality for Blountia alethes, U.S.N.M. 123b, near 

 Rogersville. Illustrated plesiotypes from the middle portion of the 

 lower limestone member of the Nolichucky (Crepicephalus zone) at 

 locality cnm/2. 



Ty/)^.?.— Holotype : U.S.N.M. 62824. Paratype: U.S.N.M. 62825. 

 Paratype pygidium of Blountia alethes assigned to the species: 

 U.S.N.M. 62822. Plesiotypes: U.S.N.M. 144580, 144561. 



COOSINA ARISTON (Walcott) 



Plate 7, figure 27 



Maryvillia ariston Walcott (part), 1916b, p. 401, pi. 64, figs. 5, 5' (not fig. 5a). 

 Coosina ariston (Walcott) Rasetti, 1956, p. 1267 (includes complete syn- 

 onymy) ; 1961, p. Ill, pi. 21, figs. 12, 13. 



Several pygidia seem identical with this species. The cranidium was 

 not identified ; it would be difficult to distinguish from that of the far 

 more common associated species C. amage. 



