4 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. IO3 



Parairvingella Kobayashi, 1938 



Glabella subconical to quadrate ; eyes moderately large ; brim con- 

 cave, with rim and preglabellar area ; anterior fixigenes present. 

 Upper Cambrian (Franconia zones), Nevada and Novaya Zemlya. 



Drumaspis, new genus (genotype, D. walcotti, new species) 



Glabella quadrate or subconical ; eyes smallest in family ; brim 

 always has well-developed rim ; anterior fixigenes very narrow, rela- 

 tively wide rearward. 



Upper Cambrian (middle Franconia zones), North America. 



CHARIOCEPHALUS HALL, 1863 



Chariocephalus Hall, i6th Ann. Rep. New York State Cab. Nat. Hist., p. 175, 

 1863; Trans. Albany Inst., vol. 5, p. 165, 1867. — Zittel, Handbook Pal., 

 Bd. 2, p. 603, Munich, 1885.— Miller, N. A. Geol. Pal., p. 538, 1889.— 

 Grabau and Shimer, N. A. Index Foss., vol. 2, p. 279, 1910. — Resser, 

 Smithsonian Misc. Coll., vol. 97, No. 10, p. 28, 1938. 



Dartonaspis Miller, Journ. Pal., vol. 10, No. i, p. 29, 1936. 



Now that a large number of species is available, the distinction 

 between Chariocephalus and Irvingella disappears, for the gap between 

 the genotypes is bridged by a series of species, so that it becomes 

 necessary to draw an arbitrary line of separation. As the line has 

 been drawn in this paper, Chariocephalus occupies a slightly higher 

 stratigraphic position than Irvingella, and thus far the two genera 

 have not been found together at any locality. The stratigraphic 

 position of Chariocephalus seems to be in the beds of upper Fran- 

 conia age. 



In view of the arbitrary separation now necessary between Chario- 

 cephalus and Irmngella, a new generic diagnosis is presented, taking 

 into account the features added by study of the many additional 

 species. It will be noted that the relative size and position of the eye 

 has become a less diagnostic criterion. 



Chariocephalus is characterized by its very large, essentially quad- 

 rate glabella that occupies nearly the full cranidial length. It may be 

 slightly expanded forward, and in rare instances constricted near the 

 midpoint. Anterior angles are usually well rounded, and the front 

 outline may be gently curved, straight, or even slightly indented. If 

 present on the outer surface, the glabellar furrows are wide and 

 shallow, but most exfoliated specimens show three pairs of prominent 

 furrows. The rear pair may be united but usually is interrupted. If 

 present, the third pair is situated so far forward that the short depres- 

 sions arise from the rounded anterior angles. Dorsal furrow usually 

 deep and wide even on the outer surface. A wide occipital furrow is 



