NO. 3 CAMBRIAN AND OZARKIAN TRILOBITES IO3 



Genus KINGSTONIA Walcott 



Kingstonia Walcott, 1924, Smithsonian Misc. Coll., Vol. 75, No. 2, p. 58. 



Description. — Cephalon semi-circular in outline, without genal 

 spines ; nearly uniformly convex, all furrows weak or quite invisible 

 externally, but the dorsal and occipital furrows more or less plainly 

 indicated on inner surface of test; a very thin rim usually striated, 

 around middle half of head. Glabella subquadrate, rounded in front. 

 not extending to the frontal groove, but leaving a wide invariably 

 undefined brim between it and the rim. Fixed cheeks rather wide, 

 eyes very small, situated nearly opposite but always behind the 

 anterior extremity of the glabella. Suture extending almost directly 

 forward from the eyes and cutting the rim abruptly. Behind the 

 eyes it runs diagonally backward and outward, ending just within 

 the genal angles. Free cheeks small, narrow. 



Pygidium relatively large, externally unsegmented without border, 

 var}ing in outline from subtriangular to transversely suboblong, 

 with convex, steeply descending and often thick edge. Axis rather 

 narrow, long, usually clearly, though never deeply, outlined on sides 

 and behind. Where the shell is removed traces of segments usually 

 observable on both the axis and pleural lobes. 



Genotype. — Kingstonia apion Walcott. 



Range. — Small trilobites belonging to Kingstonia, Ucebia, and five 

 or six related genera have been noted in the older collections for 

 many years, but more recently many species and hundreds of indi- 

 viduals have come to light. Kingstonia occurs in the upper Cambrian 

 formations of the southern Appalachians, central Pennsylvania, and 

 throughout the Rocky Mountains, A single species occurs in the 

 Ozarkian in northern Vermont. Kingstonia appears in faunas of 

 Atlantic and Arctic waters. 



KINGSTONIA APION Walcott 



Plate 16, figs. 27-283. 



Kingstonia apion Walcott, 1924, Smithsonian Misc. Coll., Vol. 75, No. 2, p. 58, 

 pi. 14, fig. 2. 



This trilobite was considered at first to be a small species of 

 Illaenurus, but comparison with specimens of the* latter led to its 

 bemg taken as the type of a new genus. The generic description and 

 figures present its more prominent characters. 



Formation and locality. — Upper Cambrian: (127) Maryville for- 

 mation. Five miles (8 km.) west of Cleveland, Tennessee. 



