408 Prof. F. M‘Coy on the Classification of 
Ceraurus Williamsi (M‘Coy). 
Sp. Char. Cephalothorax semielliptical, length rather more than 
half the width ; glabella semicylindrical, gibbous, rounded in 
front, with nearly parallel sides, three nearly equidistant, 
curved, segmental furrows on each side, the basal pair nearly 
confluent at their ends with the neck-furrow, inclosing a 
tumid ovate space on each side, separated by an undivided 
space about one-fourth of the width of the glabella; thorax 
twice the length of the glabella, axal segments large, two- 
thirds the width of the pleurz, each of which has a very large, 
diagonally cleft, oblong tubercle at its origin, beyond hich 
there is a neck-like contr action of the margin, followed at one- 
third from the axis by a hemispherical tubercle about half its 
diameter distant from the first, beyond which the distal two- 
thirds of each pleura is faiziformly dilated imto a thin, flat, 
fin-like appendage, the anterior margin of which is very con- 
vex, posterior margin slightly concave, extremity pointed ; py- 
gidium small, the six marginal spmes small, all extending to 
about the same distance backw ards, the anterior pairs there- 
fore longest ; they are thick, triangular, and three or four times 
wider than the others. Length of entire animal 1 inch 4 lines, 
of glabella 5 lines, width about 9 lines. 
The disconnected, broadly falcate, paddle-shaped pleure help 
to distinguish this beautiful little species, which by its narrow 
elongate form resembles a Remopleurides. One entire specimen 
collected from the schists at Golen Goed, Myddfai, by Mr. Wil- 
hams of Llandovery, and presented to Prof. Sedgwick by him. 
(Col. University of Cambridge.) 
Ogygia radians (M‘Coy). 
Sp. Char. Pygidium nearly semicircular, slightly convex; axis 
conical, undefined at the end, having three narrow segmental 
furrows at the anterior end, lateral lobes with three broad ra- 
diating ribs faintly divided at their axal ends by a small pleural 
furrow ; margin tumid, entire. Length 4 les, width 7 lines. 
I provisionally give this name to a small pygidium not unlike 
that of the Barrandia Cordai, but, from the duplicate lateral fur- 
rows, belonging more probably to Ogygia; probably confirma- 
tory of this view I observe in the 2nd Decade of the ‘ Geol. Surv.’ 
t. 7. f. 5. a small eight-jomted true Ogygia from Builth, having 
the pyg gidium almost identical with the present species, if, as I 
suspect, the duplicating furrows have been accidentally omitted 
(the figure alluded to is given as the probable young of the 
Ogygia dilatata (Phil.), a trilobite which has not been found at 
Builth, but abounds in the schist at Waterford). 
