CrustTacka.] LOWER PALAZOZOIC ARTICULATA. 165 
it extends to the lateral angles, which it bisects on each side: thoraa of thirteen rings, axis very convex, 
lateral lobes wider than the axis, bent down at their ends with large facets, each with a strong pleural 
groove angularly bent down and confluent at its end with the posterior margin; pygidiwm narrower than 
the buckler, semioval, with distinct seven, nine, or eleven joints, prominent axis, and broad. convex, lateral 
lobes, the segments of which are flat, about equal to the axal in number, and divided by a sulcus at 
their ends. 
CaLyMENE Bay.et (Larr.) Pl. 1. F. fig. 8. 
Ref—Barrande, Notice Prélim. p. 51. 
Sp. Ch.—Glabella about one-fifth longer than wide, not very prominent, front subtruncate, about half 
the width of the base, anterior lateral tubercle scarcely perceptible, two posterior pairs large, rounded ; 
neck-segment and furrow small; margin in front of the glabella flat, truncated in front, parallel with 
the posterior margin, less than half the length of the glabella; eyes small, on a level with the anterior 
and middle tubercle of the glabella; checks convex, nearly as prominent as the glabella near it, gradually 
becoming depressed and produced backwards into short spines at the lateral angles; surface covered with 
a minute unequal granulation. Length of head about six lines. 
This differs from the C. brevicapitata in the length of the glabella and the flat truncated margin in front 
of the glabella, while the shortness of this margin separates it from the C. Tristan and C. parvifrons, as well as 
the backward position of the eyes. 
Position and Locality—Common in the limestone of Golden Grove, Llandeilo; Sandy beds of Tre Gil, 
S. of Llandeilo. 
Explanation of Figures.—P\. 1. F. fig. 8. Cephalic shield, natural size, from Tre Gil (antennary punctures 
on each side near the front of the glabella) —Fig. 8a. Profile of ditto.—Fig. 84. Granulation magnified 
from flat plate in front of head of a specimen from the limestone of Golden Grove. 
CaLYMENE BLUMENBACHI (Brong.) 
Ref.—Murch. Sil. Syst. Pl. 7. f. 6. and 7. 
Sp. Ch—Body deep, compressed posteriorly, the pygidium and outer two-thirds of the pleura steeply in- 
clined ; cephalic shield minutely granulated, and with irregular small tubercles, semicircular, twice as wide as 
long, with the lateral angles obtusely rounded ; g/abella touching the narrow thickened anterior margin with 
its obtusely rounded front ; three flattened, spheroidal tubercles on each side, anterior one small; eyes small, 
on a level with the second tubercle; cheeks triangular, a little longer than wide, slightly convex ; pleure 
about one-fifth wider than the axis, the portions each side of the pleural furrow of nearly equal prominence ; 
pleural grooves angularly bent down about their middle, towards the posterior margin; the ends of the axal 
segments very slightly thickened: pygidiwm having the lateral and posterior edges nearly horizontal (in one 
plane), anterior margin one-third larger than the posterior, length more than half the width of the posterior 
margin, and less than half the width of the anterior margin; axis convex of seven segments, lateral lobe 
flattened, of five flattened ribs separated by strong furrows, each divided by a mesial sulcus, extending almost 
half-way from the margin; swrface of tail minutely and closely granulated, of head and body with small 
irregular tubercles among the granules. 
Position and Locality —V ery common in the Wenlock limestone of Dudley, Staffordshire; Llanwddyn, in 
the Berwyn Mountains; schists of Drummuck. . 
CALYMENE BREVICAPITATA (Portk.) Pl. 1. F. fig. 4, 5, 6. 
Ref. and Syn.—C. Blumenbachii (Port. not of Brong.) and O. brevicapitata id. Geol. Rep. t. 3. f. 1. 3. 
Sp. Ch.—In size and form resembling C. Blumenbachii, but the body narrower and flatter; the glabella 
triangular, the narrow rounded front little more than half the width of the base, and having a concave space 
between it and the thickened anterior margin equal to the width of this latter, the two together being nearly 
equal to half the length of the glabella, excluding the neck-segment ; checks triangular, about one-fifth longer 
