NO. 5 CAMBRIAN TRILOBITES 325 



bites/ and in the text, page 225, had the brief note copied that accom- 

 panied the naming of the species in 1889. This illustration of the 

 type and description were inserted to afford the means of comparison 

 with Karlia minor just before I was leaving for the field, and I did not 

 look up Dr. G. F. Matthew's paper in which he describes the same 

 form as Corynexochus roemingeri Matthew.' In this paper Dr. Mat- 

 thew calls attention to my error in assigning so large a size to the 

 species identified as Menocephalus salteri ? by Rominger, and pro- 

 poses the specific name Corynexochus roemingeri for Dr. Rominger's 

 specimens. As it was the species described and illustrated by Dr. 

 Rominger to which the name Karlia stephenensis was given, the error 

 in measurement does hot cancel that name in favor of the more recent 

 one proposed by Dr. Matthew. 



The average length of the dorsal shield of C. stephenensis is about 

 14 mm. There are seven thoracic segments, and three anchylosed 

 segments and a terminal section in the axial lobe of the pygidium. 

 The three axial segments of the pygidium are extended obliquely 

 backward on the pleural lobes as flat, broad segments separated by 

 narrow, shallow furrows. 



The specimens of this species occur in a very fine arenaceous shale 

 and none show the original test. 



A single cranidium from the Burgess shale at about the same hori- 

 zon appears to be punctate. This cranidium i mm. in length has 

 the glabella very much expanded anteriorly and large, tumid fixed 

 cheeks (pi. 55, fig. 5a). 



Formation and locality. — Middle Cambrian: (14s) Ogygopsis 

 zone of the Stephen formation; about 2,300 feet (701 m.) above the 

 Lower Cambrian and 2,700 feet (823 m.) below the Upper Cambrian, 

 at the great " fossil bed " on the northwest slope of Mount Stephen, 

 above Field on the Canadian Pacific Railroad; also (35k) Burgess 

 shale member of the Stephen formation ; on the west slope of the 

 ridge between Mount Field and Wapta Peak, i mile (1.6 km.) north- 

 east of Burgess Pass, above Field on the Canadian Pacific Railroad, 

 both in British Columbia, Canada. 



BONNIA, new subgenus 



Bonnia is proposed as a subgenus of Corynexochus with Bathyurus 

 parvulus Billings as the genotype. 



The subgenus differs from the genus in having a glabella with sub- 

 parallel sides and only slight traces of glabellar furrows ; other part: 



Smithsonian Misc. Coll., Vol. 64, 1916, pi. 36, fig. 8. 

 Trans. Royal Soc. Canada, 2d ser., Vol. 5, 1899, p. 47. 



