200 ROYAL SOCIETY OF CANADA 



and within the anterior marginal furrow. The fixed cheeks are quite 

 narrow, and in this respect, as well as others, it differs from P. Adamsi ; 

 the area of the cheeks in front of the glabella is about half of the width 

 of the anterior marginal fold, which is wide ; reversed proportions hold 

 in the species last cited. 



CONOCEPHALITES, Barrande. 



CoNOCEPHALiTES MISER, Billings. (PI. IV., figs. 7 and 7 a.) 



Conocephatites miser, Bill., Geol. Vermont, p. 950, fig. 354. 



Conoceptialites miser. Bill., Palpeoz. Fossils, vol. i., p. 12, fig. 14. 



Ptychoparia miser, Walcott, U. S. Geological Survey, Bull. 30, p. 199, pi. xxvii., 



fig. 2. 



Ptychoparia miser , Walcott, Fauna of Oienellus Zone, p. 651, pi. xcvi., fig. 8. 



Billings had only the glabella when he described this species, but 

 among the exaraj^les in the museum collection are three heads, two of 

 which have exactly the features described by that author.^ They are 

 more perfect, showing the whole of the middle piece of the head-shield ; 

 from this the species appears to be a true Conocephalites, though with a 

 somewhat short eyelobe. The glabella reaches the front marginal furrow, 

 and the fixed cheeks are not much wider within the eyelobes than the 

 lobes of the glabella; the posterior angles of the middle piece are narrow 

 and prolonged. 



The third head shows varietal differences. It is a quarter longer 

 than the others, has more deeply cut furrows, and of these the middle 

 pair are scarcely connected. 



This species is one of those which serves to add to the Middle Cam- 

 'brian faciès of this fauna. Except the Conocej)halites oniatus of Brogg. 

 from the Paradoxides beds of Norway we do not know of anj'^ species of 

 this type from Lower Cambrian beds, but it appears in the Fauna of Hof 

 in Bavaria (C. Wirthi), in the St. Croix Fauna of the Mississippi 

 valley (Dikelocephalus misa), and elsewhere in the Middle and Upper 

 Cambrian rocks. 



Altogether it seems to the author that so far as one can form a judg- 

 ment from a comparison of Billings's species with those of other countries 

 where the exact horizon of the resembling species is known, it would be 

 in favour of a Middle rather than Lower Cambrian age for his Primor- 

 dial trilobites, e'-c, of Swanton and Anse au Loup. 



1 Billings's remark that the " width of the glabella in the middle is etjual to half 

 of its length " agrees if the occipital ring be included in this measurement. 



