154 G. F. MATTHEW ON CAMBRIAN FAUNAS 
glabellar furrows; neck segment with a strong triangular projection backwards; neck 
furrow all across, but usually obscurely impressed. Jn some specimens the front of the 
head has a thick, convex, marginal rim, separated from the front of the glabella by a narrow 
groove ; in others this rim is scarcely at all developed. The eyes, shown by the form of the 
lobe, appear to have been semiannular, and about one-third the length of the head. The 
surface appears to be smooth. The following are the dimensions of the best preserved 
specimen :—Length of the head, including the large posterior projection, six lines; width 
of the convex, marginal rim, one line; width of grooye between the rim and the front of 
the glabella, one-third of a line; length of the glabella including the projection, five and 
two-thirds lines; width of the glabella at the posterior margin, three lines; width of the 
fixed cheek from the centre of the edge of the eyelobe to the side of the glabella, two 
lines. A line drawn across the head, at two and a quarter lines from the front margin, 
would pass through the anterior angles of the eyes. The length of the eye appears to be 
nearly two lines. As above remarked, this species varies somewhat in its proportional 
length and width, and hence, the dimensions above given would not be found to be 
exactly parallel in all the specimens. Occurs in the grey limestone of Topsail Head, and 
also in the pinkish limestone of Brigus, Conception Bay.” 
The woodcut in “ Palaeozoic Fossils” does not give an accurate representation of this 
species ; the centre piece of the head is rather longer than wide, and has a long spine 
projecting backward from the occipital ring; there is a peculiar sharp angulation at the 
posterior margin ; this has the appearance of a tubercle, and projects upward and back- 
ward. The eyelobes are long, heavy and much depressed at the extremities. The surface 
of the test appears smooth to the naked eye, but when viewed with a lens is seen to be 
minutely punctate. 
There is a variety (or it may be another species) in the limestone at Brigus and 
Topsail Head, Conception Bay, which is a third larger than the dimensions given for this 
species by Mr. Billings; in this the glabella is longer and more cylindrical; and in the 
young of the variety the furrows of the glabella are more distinct and the cheeks are not 
so gibbous. 
Both length and width of the centre piece of the head shield, in the examples received 
from Mr. Howley, are 13 millimetres, and the height 6 mm.; they are from the same 
localities as those studied by Mr. Billings. 
This species departs considerably from the type of Agraulos, and should be the type 
of a subgenus; in the marked elevation of the parts of the head shield, the long eyelobes 
and the depressed anterior limb of the cheeks, it resembles Ellipsocephalus ; in the short and 
direct posterior extension of the facial suture, it also resembles this genus ; the prominent 
glabella, with depressed area behind the anterior margin of the head-shield, are points of 
resemblance to Liostracus.’ If it is compared to Agraulos proper, it may be said to be 
more nearly allied to A. difformis than to A. ceticephalus, more especially to certain varieties 
of the former species found, by Prof. W. C. Brégger, in the Cambrian rocks of Norway.’ 
I would suggest, for this Newfoundland species and the allied species in the St. John 
basin, the subgeneric name of Strenueila. 

1 Liostracus proper as described by Angelin, not as in Linnarsson’s and Brégger’s modifications of the genus. 
2 
* See Plate iv. figs. 3 and 4, “Om Paradoxides skifrene ved Krekling,” 
