NO. 5 CAMBRIAN TRILOBITES RESSER 3 



Species formerly referred to Acrocephalites: 



A. americanus = Alokistocare A. insignis = Acroceplialops 



A. aoris = Alokistocare A. majtis =i Alokistocare 



A. aster = Deiraccphalns A. miiltisegmentus ^=. Deiraccphalus 



A. glomeraius = Modocia A. tutus = Acroceplialops 



A. haynesi = Bolaspis A. vulcanus = Billingsaspis 



ACROCEPHALOPS Poulsen, 1927 



Acroceplialops Poulsen, Meddels. Grjzinland, vol. 70, p. 275, 1927. 



Numerous species formerly referred to Acrocephalites belong to 

 this genus. At present all forms so identified are confined to the Ap- 

 palachians and Greenland. 



Dmgnosis. — Cranidium with tapering glabella, furrowed ; fixed 

 cheeks wide, sometimes upturned from the well-defined dorsal fur- 

 row ; eyes moderately small ; eye lines heavy ; brim wide, with median 

 boss (usually) and a narrow thickened rim of even width. Free cheeks 

 with no peculiar characteristics. Surface granulated or lined. 



Thorax and pygidium not known. 



Comparisons. — Acroccphalops differs from Alokistocare primarily 

 and chiefly in the presence of a thickened rim, narrow and of even 

 width nearly to the anterior angles. From Bolaspis it is less clearly 

 separated, the distinguishing criteria being the flatter shield, wider 

 fixed cheeks, eyes apparently never stalked. 



Genotype. — A. gibber Poulsen. 



Range. — Possibly confined to the jMiddle Cambrian of the 

 Appalachians and Greenland. 



DESCRIBED SPECIES REFERRED TO ACROCEPHALOPS 



Acroccphalops tutus (Walcott) 



Acrocephalites tutus Walcott, Smithsonian Misc. Coll., vol. 64, no. 3, p. 181, 

 pi. 24, figs. 6, 6a, 1916. 



Middle Cambrian, Conasauga; (loc. 141) near Cave Spring, 

 Georgia. 



Cotypcs.—U.S.'K.M. nos. 61566, 61567. 



Acrocephalops insignis (Walcott) 

 Acrocephalites insignis Walcott (part), Smithsonian Misc. Coll., vol. 64, 

 no. 3, p. 179, pi. 25, fig. I (only), 1916. (Not figs, la, ib = A. nitida.) 



Again, several species were included under one name and must, 

 therefore, be separated. The name insignis is retained for the forms 

 with the strongest sculpturing. 



