92 WHITE AYES ON FOSSIL FISHES FEOM 



matiou in regard to tliis species. The eye, in this specimen, is placed very far forward 

 and it seems to have been surrounded by a complete circle of about twenty-six small 

 circumorbital plates. These plates are rectangular in ovxtliue, a little longer than broad 

 and are all of exactlj'^ the same length. There were probably also three circumorbital 

 plates in P. curium, thovigh only the inferior and the posterior suborbitals are preserved 

 in the siJecimen now under consideration. In their shape and relative position, these 

 two suborbitals, as well as the large praeoperculum which lies immediately behind them, 

 are exactly similar to the corresponding plates of Eusthenopleron. 



The maxillEe are very slender in front and slightly exj)auded at their upper margins 

 behind. Their lower and tooth-bearing margins are nearly straight, and their upper 

 margins are shallowly concave in front and gently convex behind. The two jugular 

 plates are much longer than broad. They widen gradually backward and are acutely 

 pointed in front and narrowly rounded behind. 



Descriptions of Species from the Lower Devonian Rocks at CampbeUton, N. B. 



Cephalaspis Campbelltonensis, Wliiteaves. 



(Plate X, fig. 2.) 



Cephalaspis Camj/belltonensis, Whiteaves, 1881. Can. Nat. and Quart. Jour. Sc, N. S., Vol 

 X, p. 98. 



Head shield (the only part known) large, somewhat pointed in front, obliquely 

 rounded at the sides anteriorly and produced behind into moderately elongated, slightly 

 incurved cornua. Maximum breadth aboixt seven inches. Orbits varying in oiatline from 

 nearly circular to longitudinally broad ovate, subcentral, approximated, and placed at 

 distances from each other varying in diiferent specimens from once to thrice the diameter 

 of the orbit itself. Antorbital prominences rounded-conical ; interorbital prominence 

 also conical but somewhat elongated longitudinally ; postorbital valley bounded by two 

 narrow raised ridges, each of which starts from a prominence immediately behind the 

 orbit ; about half way between the orbits and the posterior margin these ridges coalesce, so 

 as to form a single, broad and prominent but somewhat obscurely defined, posterior ridge. 



Outer surface, which is very rarely preserved, polished and almost smooth to the 

 naked eye. When examined under a lens it is seen to be minutely and densely pitted, 

 the pits being very irregular in their shape, size and method of arrangement. Where 

 the enamel is removed the surface is divided into numerous well marked polygonal areas. 



Large specimens of the head-shield of this species are abundant in the Oampbellton 

 breccia, but the most perfect ones yet obtained do not show the outline of the whole of 

 the posterior margin of the shield very clearly, the contour of that part of the head being 

 slightly restored in the figure on Plate X. The orbits and the prominences and depres- 

 sions in the central portion of the shield are often well defined, but the specimens are 

 always crushed and nearly always exfoliated. Portions of the. true outer layer of the 

 test have been seen only on the central portion of the outer margin of the sides of one 

 large fragment and on the extremities of the corni^a in two or three other specimens. 



