216 F. R. Cowper Reed— Fossils from Dufton Shales. 
imperfect pygidium form. the material available. The head-shield 
much resembles that of the species termed 4. evoluta, by Tornquist,? 
from the Zeptena limestone, but the pygidium of this form is unknown. 
A new species (undescribed) from the Starfish Bed, Girvan, also 
possesses many points of similarity, both in the head and pygidium. 
The free-cheek is somewhat like that of A. callipareos, Wyv. Thomson.? 
HoMatLonorus ascriprus, sp. nov. Pl. XVII, Figs. 4-8. 
There is an imperfectly known species of Homalonotus occurring 
in the Dufton Shales which differs in certain particulars from 
H. bisulcatus, to which it is allied, and may be separated as a new 
species under the name ascriptus. The glabella is narrower, longer, 
and more cylindrical, the sides are nearly straight and the anterior 
end is more abruptly truncated, resembling in these respects that of 
the small head-shield from Horderley, figured by Salter (Mon. Brit. 
Trilob., pl. x, fig. 10), which he considered might possibly belong to 
HH. Edgelli, a species founded on a pygidium. Close to the base of 
the glabella the axial furrows, which are deep, straight, and not 
sinuous (as they are in #. bisulcatus), diverge a little. ‘The cheeks 
are narrower, more elevated and swollen, especially in the young 
individuals (Figs. 6, 7), than in the last-named species, particularly 
near the eyes, which are placed rather further forward. The 
pre-glabellar portion of the head-shield is narrower, being only 
about one-fourth the length of the head-shield, and is flattened 
and bent upwards, while the anterior margin of it is_ straight. 
The occipital segment and furrow seem developed as in Z/. bisuleatus. 
The anterior branches of the facial sutures run back to the eyes 
almost parallel, and the posterior branches curve out strongly in the 
usual way from the eyes, bending back finally to cut the posterior 
margin at a distance from the axial furrows about equal to the 
whole basal width of the glabella. The free-cheeks are unknown. 
A remarkable feature is that on the larger specimens the whole surface 
of the head-shield is covered with closely set small tubercles, which 
near the anterior lateral angles of the glabella are developed on the 
cheeks into minute erect sharp spinules, and this character alone 
would seem sufficient to separate this species from H. bisulcatus. 
In the smaller specimens referred somewhat doubtfully to this 
species the surface of the shell is not preserved, but the eyes and 
cheeks are more perfect (Figs. 6, 7). 
A small hypostome (Fig. 8) about 3 mm. long, of a sub-quadrate shape, 
may belong to this species; it is nearly parallel-sided and as wide as 
long; the body is rounded, weakly convex, clearly marked off from the 
border, has a pair of long lateral furrows running obliquely back from 
the anterior corners at asmall angle to the sides for about three-fourths 
its length; the border is rounded and somewhat swollen at the sides 
with small obtuse anterior wings; the posterior border is wider, 
marked off by a strong furrow deepened at the ends. 
1 Tornquist, Siljans. Trilobitf. (Sver. Geol. Undersokn., 1884), ser. c, No. 66, 
p. 28, t. i, fig. 54. 
* Reed, Girvan Trilobites, 1904, vol. ii, p. 112, pl. xv, figs. 11, 13. 
