50 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 148 



COOSELLA PERPLEXA (Palmer) 



Plate IS, figures 19-26 



Crepicephalus? perplexus Palmer, 1954, p. 7Zi, pi. 77, figs. 1, 2, 4. 



Represented in the collections by numerous cranidia and pygidia 

 and a few free cheeks. Careful comparison with topotype specimens 

 and further material from Nevada identified by Palmer (private com- 

 munication) failed to disclose any significant difference, hence the 

 identification seems highly reliable. 



Palmer tentatively referred the species to Crepicephalus rather than 

 Coosella because of the stratigraphic position rather than morphology. 

 The cranidia of the two genera are indistinguishable, and it has been 

 customary to refer to Crepicephalus the forms with pygidia extended 

 into a pair of lateral spines, to Coosella those with a pair of rounded 

 lobes more or less separated by a median notch. Hence the reference 

 to Coosella seems indicated in the present case. Other species of Coo- 

 sella, e.g., C. planicauda, occur in the upper Crepicephalus zone, hence 

 there is no stratigraphic discontinuity in the distribution of the genus. 



Occurrence. — Basal beds of the Aphelaspis zone in collections cno/ 

 14, Russell Gap, and cno/15. Three Springs. 



ry/)^j.— Plesiotypes: U.S.N.M. 144577-8. 



COOSELLA, species undetermined 



Plate 6, figure 19 



A single pygidium was collected. It has a short axis and wide, flat 

 pleural lobes with a slight median notch in the posterior margin. The 

 axis is extended into a long, narrow postaxial ridge. This specimen 

 resembles a pygidium of an unnamed species of Coosella figured by 

 Palmer (1954, p. 730, pi. 79, fig. 1) but the sides are straighter and 

 the posterior angles not so widely rounded. 



Occurrence. — Lower portion of lower limestone member of the 

 Nolichucky {Crepicephalus zone) at locality cnk/1. 



Disposition oj material. — Figured specimen : U.S.N.M. 144579. 



Genus COOSINA Rasetti, 1956 



Type species. — Maryvillia ariston Walcott (part) . 



COOSINA AMAGE (Walcott) 



Plate 7, figures 14-22 



Blountia amage Walcott, 1916b, p. 398, pi. 64, figs. 3, 3a. 



Blounfia alethes Walcott (part), 1916b, p. 397, pi. 64, figs, lb, Ic (only). 



Coosella amage (Walcott) Resser, 1938a, p. 70, pi. 13, figs. 12, 13. 



Available material. — Blountia amage was based on a proper com- 

 bination of cranidium and pygidium, both represented by specimens 



