VOL. XIX. (2) 
USK INLIER (APPENDIX) 
169 
Horizon and Localities . — Ludlow beds (i) by roadside 
East of Usk Castle ; (2) at Trostra Common ; and (3) in old 
road leading North from Llandegvetli and one mile from the 
Church. 
Phacops (Phacopsidelia) Stokesi, Milne Edwards, var. nov. 
uskensis [PI. VIII., figs. 13-16.] 
DescripHo)i. — Head-shield semi-circular ; gcnal angles blunt, but not 
rounded, the lateral and posterior margins meeting at about 75°. 
Glabella trapezoidal, increasing considei'ably in width anteriorly, ob- 
tusely angulated in froirt. Frontal lobe large, transverse, fully half the 
length of glabella ; anterior lateral angles slightly overhanging. First lateral 
furrows situated at nearly half the length oi glabella, composed of two 
portions meeting at about 120°, the outer part being short, straight, or slightly 
sinuous, directed back at about 20° to axial furrow, the inner portion being 
transverse, arched, extending about one-third across the glabella on each side 
and curving back so as nearly to meet the third lateral furrow and to deline a 
sub-circular lateral lobe. Second lateral furrows weak, short, isolated, nearly 
obsolete, only the inner portion being developed and not reaching axial furrow. 
Third lateral furrows situated far back, close to base of glabella, deeply im- 
pressed at sides, concave forward and bounding posteriorly the sub-circular 
lateral lobes, on which the second lateral furrows are impressed ; the third 
furrows are connected across the base of glabella by a broad shallow depres- 
sion ai'ched forward, and marking off a narrow but distinct basal ring swollen 
into a weak median tubercle. Behind the deep lateral portions of the third 
furrows this basal ring is depressed and constricted, forming small subnodular 
transverse third lateral lobes. Median basal portion of glabella somewhat 
swollen. Meso-occipital ring rounded, wider and higher than basal ring, and 
marked off by strong meso-occipital furrow deepening into conspicuous pits 
at the sides similar to the tliird lateral furrows. 
Axial furrows strong, curving sliglitly inwards immediately behind 
the anterior lateral angles of the frontal lobe, then running back sub- 
parallel and nearly straight to the base of head-shield. 
Surface of glabella smooth, except for 2-4 sub-parallel rows, of 5-6 
tubercles running back from the front margin of glabella to form an acute 
V-shaped ornament on the frontal lobe, with its apex level with its first 
lateral furrows. 
Checks incompletely known ; eyes rather large, raised on swollen base, 
reaching from about first to third lateral furrow. Marginal furrow broad, 
shallow ; border rounded. Pleuro-occipital furrow slightly concave forwards. 
Facial suture cuts lateral margin rather behind level of inner portion of first 
lateral furrow. 
Pygidium somewhat subquadrate-rounded. Axislarge, convex, prominent, 
slightly tapering to blunt extremity, extending about four-fifths the length of 
pygidium, and nearly one-third its width, compo.sed of 5-6 complete distinct 
rings followed by 2-3 fainter, narrower ones. Pleural lobes gently arched 
down, convex, composed of 4-5 pleurae, of which only the first three are 
usually distinct ; pleural furrows strong, deep, dying out at about three- 
fourths the length of the pleurae. 
Horizon and Localities . — In WenUn'k limestone in (1) 
Stream below quarry, 300 yards Norllt-Easl oi Greenpool 
