NO. 3 UPPER CAMBRIAN TRILOBITE FAUNAS — RASETTI 53 



scribed under various names from other areas, such as C. dakotensis 

 Resser, C. albertensis Resser, C. modesta Lochman, C. grandis Loch- 

 man are distinct from the present species. In any case, the trivial name 

 alethes would be the proper one for the species from Tennessee since 

 it has priority. 



Occurrence. — Type locality is U.S.N.M. 123b, near Rogersville. 

 Common in the uppermost beds of the lower limestone member of the 

 Nolichucky (Crepicephalus zone). Localities cnn/1 to cnn/4, cnn/19, 

 and cnn/1 6 ; rare in somewhat lower beds (loc. cnm/2) . 



Types.— Kolotype: U.S.N.M. 62821. Plesiotypes: U.S.N.M. 

 144582-6. 



COOSIA ROBUSTA Walcott 



Plate 7, figure 26 



Coosia robusta Walcott, 1911, p. 97, pi. 16, figs. 2, 2a. 



Coosia robusta Walcott, Resser, 1938a, p. 70, pi. 11, figs. 12, 13. 



Several pygidia associated with the preceding species seem identical 

 with the types ; however, no cranidia could be identified. The pygidium 

 differs from that of C. alethes in the longer axis and almost entirely 

 convex surface. The largest pygidium found is 25 mm. long and 40 

 mm. wide. 



Occurrence. — Type locality is U.S.N.M. 107, NW. of Knoxville. 

 Collected from the uppermost beds of the lower limestone member of 

 the Nolichucky (Crepicephalus zone) at localities cnn/1, cnn/2. 



Ty/'^.y.— Cotypes : U.S.N.M. 57590, 57591. Plesiotype: U.S.N.M. 

 144587. 



COOSIA, species undetermined 



Plate 5, figure 19 



Known from a single pygidium. Axis stout, prominent, slightly 

 tapered, rounded posteriorly, somewhat over half the pygidial length, 

 extended into a short postaxial ridge. Pleural regions flat, with straight 

 anterior and posterior outlines that give the entire pygidium a rec- 

 tangular appearance. Pleural furrows, except the first pair, almost 

 indistinct, curving backward. Surface of posterior portion of pleural 

 regions with transverse wrinkles. Length 3.0 mm., width 8.0 mm. 



This pygidium differs from the associated species of Coosia in its 

 subquadrate shape. 



Occurrence. — Upper portion of lower limestone member of the 

 Nolichucky (Crepicephalus zone) at locality cnn/1. 



Disposition of material. — Figured specimen : U.S.N.M. 144588. 



