Point Levi Fossils, 



309 



The pleurae which seem to belong to this species are broad, 

 flat, falcate and with a moderately strong groove running obliquely 

 nearly their whole length. 



Judging from the form of the three pygidia figured by Angelin 

 on Plate 41 of the Palaeontologia Scandinavica, it appears pro- 

 bable that this species connects Dikelocephalus with Centropleura 

 a genus which occurs in the base of the Lower Silurian of Swed- 

 en, in Regio B and C of Angelin. It is perhaps an extreme form 

 but the course of the facial suture and characters of the 

 glabella are the same as they are in Dikelocephalus, The py- 

 gidium differs from D. Minnesotensis in having fewer ribs and a 

 greater number of spines, but this difference is not of itself I 

 think of generic value. 



Limestone, No. 1. 



Dikelocephalus planifrons. N . s. 

 Fig. 6. 



Description, — Head with a broad smooth margin in front, the 

 width of which is about equal to the width of the glabella : the 

 latter oblong conical rather flat most elevated along the median 

 line, broadly rounded in front, its sides nearly straight and sub 

 parallel slightly converging from behind forwards. On each side 

 of the median line there are three or four obscure depressions 



Fig. 6. Fig. 7. Fig. 8. 



Fig. 6 — .D. planifrons. 

 Fig. 7.— D. Belli. 

 Fig. 8. — D. Oweni. 



which represent the glabellar furrows. The length of the gla- 

 bella appears to be about once and a half its width at the neck 

 segment. Eyes, cheeks, thorax and pygidium unknown. Length 

 of largest head seen, twelve lines ; length of glabella, seven lines ; 

 width of glabella at base five lines, at front margin four lines and 

 a half. 



