NO. 13 DIKELOCEPHALUS AND OTHER GENERA 349 



elongate pygidium. It differs from Osceolia in frontal limb of 

 cephalon ; presence of occipital spine and character of pygidium. 



Further observations on the genera will be found under the descrip- 

 tion of each genus. 



SYNONYMIC REFERENCES 



The following is a list of the species that have been referred to 

 Dikelocephalus ' and which are now referred to other genera. It is 

 only approximately complete, as many references that occur in text- 

 books and in general discussion of the fauna are omitted. 



FORMER GENERIC REFERENCE. PRESENT GENERIC REFERENCE. 



Dikelocephalus afUnis Billings (Geol. Surv. 



Canada, Pal. Foss., Vol. i, 1865, p. 197) Platycolpus Raymond.^ 



Dikelocephalus angusticauda (Angelin) Lin- 



narsson, Brogger (Die Sil. Etagen 2 und 3, • " 



Kristiania, 1882, p. 126) Apatokephalus Brogger. 



Dikelocephalus {? ) angustifrons Walcott 



(Monogr. U. S. Geol. Survey, Vol. 8, 1884, 



p. 42, pi. 10, figs. I, la, lb) Lisania Walcott. 



Dikelocephalus barabuensis Whitfield (Ann. 



Rep. for 1877, Wis. Geol. Survey, 1878, p. 63) .Platycolpus Raymond. 

 Dikelocephalus ? baubo Walcott (Proc. U. S. 



Nat. Museum, Vol. 29, 1905, p. 91) Ptychaspis Hall. 



Dikelocephalus ? bavaricus (Barrande) Brog- ■ 



ger (Nyt Mag. for Naturvid., Vol. 36, 1898, 



p. 212) Genus undt. 



Dikelocephalus belli Billings (Geol. Surv. 



Canada, Pal. Foss., Vol. i, 1865, p. 403, text 



fig. 378) xinomocarella Walcott. 



Dikelocephalus billingsi Linnarsson (Geol. 



Foren. Stockholm Forhandl., Vol. 2, 1875, p. 



492, pi. fig. I ) Acerocare Angelin. 



Dikelocephalus bilobatus Hall and Whitfield 



(U. S. Geol. Expl. 40th Pari., Vol. 4, 1877, p. 



226, pi. 2, fig. 36) Platycolpus Raymond. 



Dikelocephalus ? brizo Walcott (Proc. U. S. 



Nat. Mus., Vol. 29, 1905, p. 92) Ptychaspis Hall. 



Dicellocephalus broggeri Moberg (Aftryck ur 



Kongl. Fysiogr. Sallsk. Handl. Lund, Bd. 17, 



1906, p. 87, pi. 5, figs. 7, 8) Genus undt. cf. Platycolpus 



Raymond. 



^ The original spelling of the genus is adhered to in this paper, but under 

 synonymic references the spelling used by each author has been retained, the 

 alphabetical sequence according to species names being followed. 



^Memoirs Victoria Memorial Museum, Geol.* Survey Canada, Bull, i, 1913, 

 p. 63. 



