96 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 148 



APHELASPIDELLA MACROPYGE Rasetti, new species 



Plate 11, figures 1-8 



Available material. — Numerous cranidia, free cheeks, and pygidia 

 excellently preserved in limestone. 



Description. — Cranidium of low general convexity. Glabella 

 straight-sided, subtruncate in front, of low convexity, defined by a 

 shallow axial furrow. Glabellar furrows barely indicated on outer 

 surface; occipital furrow shallow, occipital ring short (sag.) and 

 simple. Frontal area 0.8 times the glabellar length ; preglabellar field 

 convex, slightly downsloping; border furrow deep, with a median 

 inbend; border somewhat convex, wide medially, tapering in width 

 at the sides. Palpebral area half as wide as the glabella, slightly up- 

 sloping. Ocular ridges faint, transverse. Palpebral lobes 0.3 times the 

 length of glabella plus occipital ring, defined by a very shallow pal- 

 pebral furrow. Anterior sections of facial suture forming an angle of 

 almost 60° with the median line ; anterior angles of cranidium more 

 widely rounded than in any species of Aphelaspis ; marginal portion of 

 suture about one-third the length of anterior cranidial margin, as in 

 most Aphelaspis species. Posterior section of facial suture first directed 

 backward, curving outward, then again somewhat backward, defining 

 slender posterior area identical with that of most Aphelaspis species. 

 Free cheek with well-defined lateral border. 



Pygidium twice as wide as long, subelliptical. Axis rapidly tapered, 

 showing 3 rings and a terminal section, less than half the pygidial 

 length, extended into a long postaxial ridge. Three pairs of increas- 

 ingly shallow pleural furrows and less distinct interpleural grooves 

 are visible ; the furrows extend, very broad and shallow, even across 

 the wide, concave border. The inner edge of the doublure is clearly 

 apparent on the upper surface. 



Surface of test smooth, except for a dense row of puncta in the 

 anterior border furrow. Length of largest cranidium 18 mm. Length 

 of largest pygidium 9 mm., width 18 mm. 



Occurrence. — The type locality is author's locality cnr/4, Lost 

 Creek. Also common in collections cns/20, cns/20a, Washburn, and 

 present in collections cns"/15, Three Springs, and U.S.G.S. 2970. In 

 the U.S. National Museum there is a collection of cranidia and pygidia 

 of the species from locality 173, marked "Maryville, Tenn." which 

 is also the type locality for Aphelaspis arses. 



Types.— B.o\oiy^e\ U.S.N.M. 144681. Paratypes: U.S.N.M. 

 144682. 



Genus PARAPHELASPIS Rasetti, new genus 



Description. — Cranidium with considerable relief. Glabella well ta- 

 pered, truncate in front, fairly convex transversely, defined by a deep 



