NO. 3 UPPER CAMBRIAN TRILOBITE FAUNAS — RASETTI 113 



row broad and deep; occipital ring short (sag.), but extended into a 

 very long, uptilted spine. Frontal area consisting of convex, down- 

 sloping, preglabellar field and elevated, convex, transversely arched 

 border. Ocular ridges wide and fairly prominent, directed slightly 

 forward from the glabella, curving slightly to assume a transverse di- 

 rection. Palpebral area somewhat wider than glabella, rising above the 

 axial furrow and strongly convex transversely. Palpebral lobes and 

 posterior area not preserved. Surface of glabella and fixed cheeks cov- 

 ered with granules of different sizes. Length of cranidium 4.2 mm. 

 exclusive of occipital spine. 



This cranidium, remarkable for the pointed glabella, wide palpebral 

 area, and forward-directed ocular ridges, cannot be assigned to any 

 described genus. No affinities can be suggested, beyond its inclusion in 

 the great ptychoparioid group. 



Occurrence. — Lower portion of lower limestone member of the Noli- 

 chucky (Crepicephalus zone) at locality cnk/1. 



Disposition of material. — Figured specimen: U.S.N.M. 144730. 



Undetermined Pygidium No. 1 

 Plate 6, figure 8 



Known from a single example. Pygidium 2.5 times as wide as long. 

 Axis prominent, tapered, showing 3 rings plus a terminal section, 

 reaching the border furrow. Pleural region with a straight anterior 

 outline, rounded anterior angles, and posterior margin fairly straight 

 on either side, slightly pointed medially. Three pairs of rather deep 

 pleural furrows and shallow interpleural grooves are present. Border 

 furrow shallow, border very narrow. 



This pygidium somewhat resembles the pygidia of Llanoaspis, dif- 

 fering in its shortness and small number of pleural furrows. No cran- 

 idium to which it may be assigned was collected from the same beds. 



Occurrence. — Lower portion of lower limestone member of the Noli- 

 chucky {Crepicephalus zont) at locality cnk/1. 



Disposition oj material. — Figured specimen: U.S.N.M. 144731. 



Undetermined Pygidium No. 2 

 Plate 6, figures 20, 21 



Known from several examples. Pygidium of low convexity, 1.75 

 times as wide as long. Axis long, tapered, straight-sided, extended into 

 a sharp postaxial ridge that reaches the posterior margin. Seven or 

 eight axial rings separated by shallow furrows are distinguishable. 

 Pleural regions with straight anterior outline, well-rounded anterior 

 angles, and regularly semicircular posterior margin except for a shal- 



