166 BRITISH PALA.OZOIC FOSSILS. [CrusTacza. 
than wide, the part anterior to the eyes elevated into a gibbous, oblique, ridge running inwards and forwards 
towards the margin, the posterior half gently convex ; antennary pores large; eyes small, in the middle of the 
width of the cheeks, extending from the top of the basal to the top of the middle tubercle of the glabella ; aais 
of the body exceeding the width of the pleure: by nearly one-fifth, and having tubercles at each end nearly 
one-third of the width of the axis in length; the line of angulation of the pleural furrows, and at which the 
pleuree bend down, is about one-third the width of the pleure from the axis near the head, but gradually 
approaching the axis towards the tail ; tai/ minutely granulose, flattened, about seven or eight segmental furrows 
in the axis, and seven flat lateral ribs, separated by narrow sulci, and each divided by a fine mesial line. 
The triangular narrow-fronted glabella, with the space between it and the margin, and the strongly ridged 
cheeks in front of the eyes, distinguish the head from C. Blumenbachii; the great proportional width of the 
axis, with the very large tubercles at the ends of the segments, distinguish the body, and the flatness of the 
lateral ribs, their duplicating furrows extending to the axis, and narrow divisional sulci, distinguish the tail 
from the same. The great width of the axal, and narrowness of the lateral lobes, separate the body from 
that of the ©. tuberculosa (see the latter), while the less wide and flat anterior margin, and the width of the 
base of the glabella equalling, or a little exceeding the cheek, separate the head. I cannot think, with 
Mr Salter (Mem. Geol. Surv.) this species referrible to the C. parvula of Barrande and Beyrich, in which the 
position of the eyes is much further back (on a level with the middle of the basal lobe), the segmental furrow 
very small, and the shield as remarkably long and angulated as this is wide and obtusely rounded. It is 
possible some of the so-called varieties of the C. senaria of the American geologists may be identical with 
this species. 
Position and Locality—Abundant in the schists of Nant yr Cwm; Acton Scott, Church Stretton, 
Shropshire; Llandeilo, Caermarthenshire ; Applethwaite Common, Westmoreland; Alt yr Anker, Meifod, 
Montgomeryshire ; Mathyrafal, S. of Meifod, Montgomeryshire ; Bryn Melyn, Bala, Merionethshire; Llan- 
gynyw Rectory, Montgomeryshire. 
Explanation of Figures.—Pl. 1. F. fig. 4. Cephalie shield from the schists of Nant yr Arian (anten- 
nary punctures distinct at each side of the front of the glabella).—Fig. 5. Pygidium of ditto, from the same 
mass.—Fig. 6. Profile of head from Applethwaite Common, 
CALYMENE SUB-DIADEMATA* (M‘Coy). PI. 1. F. fig. 9, 10. 
Ref—C. diademata Barrande, Beyrich Untersuchungen, &e. t. 2. fig. 4. 
Sp. Ch.—Cephalic shield nearly twice and half wider than long; glabella broad, tumid, subcylindrical, 
front two-thirds the width of the base, very obtusely rounded, two posterior pair of lateral tubercles large, 
rounded, anterior first pair very minute; a prominent reflexed rounded margin about as thick as the neck- 
segment and rising nearly to the height of the glabella, is separated from it in front by a deep sulcus, equal 
to the thickened margin in width, the two together equal to about one-third the length of the glabella (ex- 
clusive of the neck-segment); cheeks wider than high, gibbous, particularly in front of the eyes, which are 
small, and on a level with the anterior and middle lateral tubercles ; neck-segment thick. Usual length of 
cephalic shield ten or eleven lines. 
This species differs from the Calymene brevicapitata in the greater width and obtuseness of the front of 
the glabella, the wider side-lobes of head and body, and the shorter front margin, while from C, Blumen- 
bachii it differs in the greater width of the shield, and the broad furrow and high reflexed margin in front of 
the glabella, as well as wider pleuree ; imperfect casts of the middle part of the head of the latter species 
are in some cases, however, I think, undistinguishable. 
* This fossil seemed to me perfectly identical with Beyrich’s figure of what he considered Barrande’s undoubted 
C. diademata, and I think so still, but M. Barrande assures me that these specimens are not of his species, and as his 
suggestion that they belong to C. brevicapitata, is clearly negatived by the great proportional width of the side-lobes both 
of the body and head, as well as the wider front of the glabella, I am obliged, as these sheets pass through the press, to 
propose a separate name. It is a representative of the American C. senaria of the New York Llandeilo flag, or Trenton 
limestone—differing by its greater width and the tubercular ends of the axal segments of the thorax. 
