3l6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 64 



anterior marginal spine as in the latter species. Axial lobe with three 

 or four rings and a terminal section ; pleural lobes with three broad 

 flat segments separated by narrow shallow grooves. 



All the specimens are from arenaceous shale and decomposed are- 

 naceous hmestone. 



Formation and locality. — Lower Cambrian: (25) Shaly sandstone 

 just above Parkers quarry, Georgia, Franklin County, Vermont. 



Also (48b) York formation; roadside, north of Highland Park, 

 York, York County, Pennsylvania. 



CORYNEXOCHUS CLAVATUS (Walcott) 



Plate 55, figs. 4, ^a-b 



Ptychoparia ? (Subgenus ?) clavata Walcott, 1887, American Jour. Sci., 3d 

 ser., Vol. 34, p. 198, pi. I, fig. 3. (Note on the species and illustration 

 of a cranidium.) 



Protypus ? clavafns Walcott, 1891, Tenth Ann. Rept. U. S. Geol. Surv., 

 p. 656, pi. 98, fig. 4. (Republishes note and illustration of 1887.) 



These minute cranidia, the largest 2.5 mm. in length, have the 

 characters of the typical form of Corynexochiis as illustrated by 

 figure I, plate 55, of this paper. The American Lower Cambrian 

 species difTers from C. spinulosus of the Middle Cambrian of Sweden 

 in having a broader fixed cheek in front of the ocular ridge and a 

 proportionally greater widening of the anterior half of the glabella. 

 The glabella has four pairs of furrows, the posterior pair united 

 across the glabella by a short transverse furrow. The palpebral lobes 

 are of medium size and quite prominent. Anteriorly they unite with 

 the ridge which extends across the fixed cheeks to the dorsal furrow 

 beside the glabella. 



Surface marked by irregular exceedingly fine elevated lines or 

 sharp ridges arranged concentrically about the anterior portion of 

 the glabella and more or less transversely across the posterior portion. 

 These lines can only be seen by the aid of a rather strong lens. 



Corynexochus clavatus is the oldest known species of the genus. 

 It is associated with a large and typical Lower Cambrian fauna at 

 several localities. The associated fauna includes (locality numbers 

 in parentheses) : 



Microinitra (Iphidella) panniila (White) (38a) 



Obolus prindlci (Walcolt) (38a) 



Lingulella granvillensis Walcott (38a) 



Lingulella sp. (38a) 



Botsfordia ccclata (Hall) (33, 38a, 39, 43a) 



Yorkia ? washitigtonensis Walcott (380) 



Acrotrcta emmonsi Walcott {3^11) 



