22 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 93 



Comparisons. — Compared with the somewhat older species of 

 Alokistocarc and Acrocephalops, this genus resembles both in certain 

 features. Features of the rim as well as the median ridge, which re- 

 places the boss, distinguish it from Acrocephalops, and the less ex- 

 panded brim and the well-defined rim separate it from Alokistocarc. 



Genotype. — Acroccphalites ? aster Walcott. 



Name. — Aetpas = ridged, K&^aXn<i — head. 



Range. — Possibly confined to the Upper Cambrian Crepicephalus 

 zone. 



DESCRIBED SPECIES REFERRED TO DEIRACEPHALUS 



Deiracephalus aster (Walcott) 



.Icrocephalitcs f ostcr ]]\ilcott (part), Smithsonian Misc. Coll., vol. 64, no. 3, 

 p. 178, pi. 26, figs, gb, gc, 1916. (Not figs. 9, 90 := L. buttsl.) 



Upper Cambrian, Conasauga; (loc. 22y) opposite car barn. Birm- 

 ingham, Alabama. 



Holotype. — U.S.N.M. no. 61594. 



Deiracephalus buttsi, n. sp. 



Acroccphalites / aster Walcott (part), Smithsonian Misc. Coll., vol. 64, no. 3, 

 p. 178, pi. 26, fig. 9, ga, IQ16. 



This form is similar to L. aster but differs in having fewer pustules 

 and a heavier occipital spine. 



Upper Cambrian, Nolichucky ; (loc. 107c) west base Copper Ridge, 

 II miles northwest of Knoxville, Tennessee. 



Holotype.— U.S.N.M. no. 61593. 



Deiracephalus multisegmentus (Walcott) 



Acroceplialitcs multisegmentus Walcott, Smithsonian Misc. Coll., vol. 64, no. 3, 

 p. 180, pi. 24, figs. 5, sa, 1916. 



Upper Cambrian, Weeks; (loc. 30n or 30o) 2 miles south of 

 Marjum Pass, House Range, Utah. 

 Coty pes.-— U.S.N.M. nos. 61564-5. 



DOLICHOMETOPUS Angelin, 1852 



Dolichoinefopiis Angelin, Pal. Scandinavica, pt. i, Crustacea formationis transi- 

 tionis Lipsiae, p. 72, 1852. Idem, Pal. Scandinavica, 3d ed. Holmiae, 

 p. 7-J, 1878. 



Dolichoinctopiis Walcott, Smithsonian Misc. Coll., vol. 64, no. 5, p. 355, 1916. 



Numerous trilobites belonging to many genera have been referred 

 to Dolichometopus, Corynexochus, and Bathynriscus simply because 

 their glabellae tended toward a rectangular form and expand forward. 

 Angelin referred the first two genera to his family Corynexochidae. 



