46 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 148 



Types. — Holotype of C. buttsi (pygidium) : U.S.N.M. 94907. Para- 

 types : U.S.N.M. 94908. Holotype of C. expansus: U.S.N.M. 94910. 

 Plesiotypes: U.S.N.M. 144565. 



CREPICEPHALUS CONVERGENS Rasetti, new species 



Plate 8, figures 5-8 



Available material. — Several pygidia and cranidia, the former of 

 small size, mostly preserving the test. 



Description. — Cranidium fully typical of the genus. Glabella tapered, 

 rounded in front, showing 2 pairs of shallow furrows even on the outer 

 surface ; occipital furrow straight, occipital ring rounded. Frontal area 

 divided into preglabellar field and border of about equal widths (sag.) ; 

 border slightly convex. Palpebral area and lobes as in other species of 

 the genus ; posterior area not preserved. 



Pygidium represented by better specimens than the cranidium. Axis 

 occupying two-thirds of the length, somewhat tapered, extended into 

 a short postaxial ridge which reaches the wide, indistinct border fur- 

 row. About 2 rings distinct, 1 or 2 more barely indicated. Pleural lobes 

 with rounded anterior angles, fairly straight sides converging toward 

 the rear, and concave posterior margin between the spines. Pleural 

 platforms relatively small, with 3 short, well-marked furrows, no 

 interpleural grooves; slope dropping rather steeply to border furrow 

 and wide, flat border. Spines rapidly tapered, flat, relatively short. 

 Surface finely granulate. Length of largest pygidium 6.5 mm., width 

 10.5 mm. 



Discussion. — This form is chiefly characterized by the pygidium, 

 which differs in outline, form of the spines, and relative length of axis 

 from described species. 



Occurrence. — Lower portion of lower limestone member of the 

 Nolichucky (Crepicephalus zone) at locality cnk/1. 



Types. — Holotype (pygidium): U.S.N.M. 144566, Paratypes: 

 U.S.N.M. 144567. 



CREPICEPHALUS cf. C. CONVERGENS Rasetti 



Plate 8, figures 9-11 



Several pygidia collected in strata higher than those yielding the types 

 of the species differ consistently in several features aside from the 

 different manner of preservation (these pygidia are exfoliated). The 

 sides are even more strongly convergent than in C. convergens, thus 

 bringing the spines closer together ; these are also shorter and more 

 obtuse in shape, and the margin between them more definitely notched. 



Occurrence. — Uppermost beds of the lower limestone member 

 (Crepicephalus zone) of the Nolichucky (loc. cnn/1, cnn/3). 



Dispostion of material. — Figured specimens: U.S.N.M. 144568-9. 



