92 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 148 



Pygidium more than twice as wide as long. Axis strongly tapered, 

 usually showing 1 distinct ring plus a terminal unsegmented section, 

 almost reaching posterior margin. Anterior outline of pleural lobe 

 with sharp geniculation situated about midway from axial furrow to 

 anterior angle. Two pairs of broad pleural furrows and somewhat 

 indistinct pleural grooves are visible on upper surface. Border narrow 

 all along posterior margin, poorly defined by shallow border furrow. 



In some specimens fine puncta are present in the furrows on cra- 

 nidium and free cheeks. Length of largest cranidium observed among 

 several hundred specimens 10 mm. The overwhelming majority of the 

 cranidia do not exceed 7 mm. Length of largest pygidium 1.6 mm., 

 width 4.0 mm. 



Discussion. — This is a distinctive species, that can seldom be con- 

 fused with other forms of Aphelaspis even if only a small sample is 

 available. The main characteristics are the shallowness of the axial 

 furrow, the tumid preglabellar field, the poorly defined anterior border, 

 and the relatively anterior position of the eyes. 



Occurrence. — The species is usually extremely abundant when 

 present, and represents an excellent index fossil for the upper portion 

 of the middle Aphelaspis zone. The type locality is U.S.N.M. 119, 

 S. of Morristown, Hamblen County. Present in the author's collec- 

 tions cns/1, cnt/1, cns/2, cnt/4, cnt/7, cns/15, cnt/15, cntVlS, cnt/20, 

 cnt/21, and in Oder's collection No. 14. 



Types.— Ro\oiy^&: U.S.N.M. 94927. Plesiotypes: U.S.N.M. 

 144672. 



APHELASPIS PUNCTATA Rasetti, new species 



Plate 18, figures 21-29 



Available material. — Numerous cranidia and free cheeks and a few 

 pygidia. 



Description. — Glabella of usual shape and convexity; axial furrow 

 with deep pits at anterior corners of glabella. Frontal area markedly 

 convex in front of glabella; border furrow well impressed, forming 

 rounded angle on midline; border convex, averaging in midlength 

 (sag.) one-third of length of preglabellar field. Entire frontal area 

 over half the length of glabella plus occipital ring. Palpebral area 

 somewhat upsloping; palpebral lobes elevated above palpebral area, 

 half the glabellar length, defined by distinct furrow. Distance from 

 posterior end of palpebral lobe to posterior cranidial margin less than 

 length of palpebral lobe. Anterior sections of facial suture with aver- 

 age divergence; anterior angles of cranidium very sharp. Posterior 

 area equal in width (tr.) to occipital ring. Free cheek with narrow, 

 convex border. Genal spine rapidly tapered, fairly flat on dorsal side ; 



