. Bulletin of the British Museum (Natural History), Geology. FROM CENTRAL WALES 135 pits in Ei on the left half-fringe and about eighteen on the right half. The number of pits in the anteromedian rows cannot be determined but five I arcs are present by row 9 on either side of the fringe and continue to the genal angles. Irregularities in the pit distribution occur, the holotype showing two ridges fusing between row 13 and row 14 on the left half of the fringe, and between row 8 and row 9 on the right side (PI. 3, fig. 7). The paratype OUM B179 (PL 3, fig. 4) possesses about 43 pits in the Ei a
. Bulletin of the British Museum (Natural History), Geology. FROM CENTRAL WALES 135 pits in Ei on the left half-fringe and about eighteen on the right half. The number of pits in the anteromedian rows cannot be determined but five I arcs are present by row 9 on either side of the fringe and continue to the genal angles. Irregularities in the pit distribution occur, the holotype showing two ridges fusing between row 13 and row 14 on the left half of the fringe, and between row 8 and row 9 on the right side (PI. 3, fig. 7). The paratype OUM B179 (PL 3, fig. 4) possesses about 43 pits in the Ei arc, of which about 21 are situated on the left half-fringe. The preserva- tion of the inner portion of the fringe however does not allow determination of the number of arcs developed. The facial suture is marginal, being near the bottom of the marginal band anteri- orly and tending obliquely across it laterally to be just below the marginal rim at the posterolateral corners, whence it follows the posterior border of the fringe inwards towards the fulcral processes (PI. 3, fig. 7). The genal spines are known on a single specimen, It. 2736, in which the left spine extends behind the pygidium for about six mm. The thorax is rectangular in shape, being about two and a half times wider than long. The six segments conform to the usual trinucleid pattern and require no further detailed account. The axial furrows are however better developed dorsally than in the type species. The triangular pygidium is about three times as wide as long. The posterior margin is defined by a very small raised rim marking the upper limit of the steeply declined posterior border. The convex, clearly differentiated axis may have at least nine rings present, although they are only well developed anteriorly. Up to three faint ribs may be present on the pleural fields in addition to the anterior border (PL 3, fig. 4). Biometrical data. Although relatively few specimens of this species are available, some bivar
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