6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 95 



marginal spines at the anterior angles of the pygidium. Were this a 

 Lower Cambrian form, it is doubtful that a separate genus would be 

 recognized because in Bonnia senecta (Billings) and several unde- 

 scribed species considerable expansion of the glabella takes place. 



Bonnaspis stephenensis (Walcott) 



Menocephalus salteri? Rominger (not Devine), Proc. Acad. Nat. Sci., Phila- 

 delphia, pt. I, p. 16, pi. I, fig. 6, 1887. 



Karlia stephenensis Walcott, Proc. U. S. Nat. Mus., vol. 11, p. 445, 1888; 

 Canadian Alpine Journ., vol. i, pt. 2, p. 224, pi. 3, fig. 4, 1908; Smith- 

 sonian Misc. Coll., vol. 64, no. 3, p. 224, pi. 36, fig. 8, 1916. 



Corynexochus rcemingeri Matthew, Trans. Roy. Soc. Canada, 2d ser., vol. 5, 

 sec. 4, p. 47, pi. 2, fig. 3, 1899. 



Corynexochus stephenensis Walcott, Smithsonian Misc. Coll., vol. 64, no. 5, 

 p. 324, pi. 55, figs. 5-5e, 1916. 



Middle Cambrian, Stephen ; (loc. 14s) Mount Stephen, above Field, 

 British Columbia. 



Holotype — U.S.N.M. no. 61731 ; paratypes, nos. Gzyiy, 62718. 



BONNIA Walcott, 1916 



Corynexochus (Bonnia) Walcott, Smithsonian Misc. Coll., vol. 64, no. 5, p. 325, 



1916. 

 Bonnia Raymond, Amer. Journ. Sci., 5th ser., vol. 15, no. 88, p. 309, 1928. 



Bonnia was proposed as a subgenus of Corynexochus Angelin, but it 

 is doubtful whether the two genera can remain in the same family. 

 American species were rather carelessly assigned to the two genera, a 

 relic of the earlier days of paleontology when it was customary to lo- 

 cate an existing genus to receive new forms. 



Walcott made Bathyurits parvulus Billings the genotype but based 

 his description on specimens from Bonne Bay, which represent several 

 considerably different species. Moreover, hitherto the Bonnia species 

 have been studied from a small fraction of available specimens picked 

 out of a tray because they happened to break free of the matrix. This 

 resulted in description of only a fraction of the species represented in 

 this very prolific trilobite. genus. 



The National Museum of Canada kindly lent the specimens marked 

 as Billings' types, which presumably are the ones restudied by Matthew. 

 Without access to these specimens it would have been impossible to 

 determine exactly what the described species are. Unfortunately Bill- 

 ings' type specimens were not marked by him, and consequently in 

 this case it is not possible to go back of Matthew's 1897 paper, except 

 to distinguish between the specimens available in 1861 and those sub- 

 sequently collected in 1872 by T. C. Weston, which, of course, could 



