PALEONTOLOGY OF NEW-YORK. 
306 
Fig. 6. The caudal extremity and a few articulations of the abdomen from which the crust is 
separated, showing the difference of form thus produced in this part of the fossil. 
The faint line beyond this shows the limit of the impression of the margin and spine 
in the shale. 
Fig. 7. The inner surface of the crust (separated from the specimen fig. 6), showing its extension 
laterally in a thick border beyond the marks of articulation, and posteriorly into the 
spine. 
Fig. 8. The eye of this species enlarged, showing the elevation, form and structure of the surface. 
Position and locality. Shale of the Niagara group, Lockport. 
667. 5. CERAURUS INSIGNIS. 
Pl. LXVII. Figs. 9 & 10. 
See page 300 of this volume. 
Buckler nearly semicircular, with the posterior angles extended into sharp spines ; glabella 
clavate, lobed ; anterior portion very convex, a little extended laterally beyond the posterior 
portion, and causing the longitudinal furrow to form a curve at this point; the posterior lateral 
furrow oblique, reaching to the centre, and joining the transverse furrow at the base of the 
glabella ; the posterior lobes are thus circumscribed, and triangular in form ; the anterior and 
second furrow are sharp, and almost directly transverse or slightly arched ; surface granulate, 
granulations unequal in size ; surface of cast punctate. 
The fragments of this species correspond so well with the figures of Beyrich, that I can have 
no doubt of the identity of our species with the Bohemian one. It is only recently that I have 
discovered, among some old collections, the two fragments figured, and I had previouly supposed 
that the genus was confined to the Lower Silurian period*. The fragments preserve so strongly 
the characteristics of Ceraurus, that I can not hesitate for a moment to refer it to that genus, 
which has precedence in point of time over Cheirurus ; and the figures of this and other 
species given by Beyrich show conclusively that the two are identical. 
Fig. 9. The central portion of a cephalic shield, preserving the form and proportions of the 
glabella and the outer crust in part, with the spine at one of the posterior angles. 
Fig. 10. Another similar fragment, where the base of the eye is preserved on one side, with the 
posterior spine of the buckler. The anterior portion is broken, and the extension in 
front may be due to pressure. 
Position and locality. In the shale of this group at Rochester. 
* It is only since the publication of the first volume of the Palaeontology of New-York, that I have seen the papers 
of Beyrich cited above. 
