PELTURA PUNCTATA. 99 



of the species. This is particularly the case with those from the Malvern Hills, 

 which are, moreover, usually smaller than the Scandinavian specimens. Salter, 

 indeed, supposed at one time that the British specimens constituted at least a 

 distinct variety, which he called var. obesus ; but in the Survey Memoir on North 

 Wales he appears to have given up this distinction. Our British specimens, 

 indeed, are not sufficiently well preserved to admit of minute differentiation. 



As a rale, there is very little difficulty in recognising the genus, even when the 

 remains are very fragmentary. The width of the glabella and the forward position 

 of the eyes are usually sufficient to distinguish the head, while the thorax is 

 characterised by the breadth of the axis and the form of the pleune. The present 

 species is distinguished from V. punctata by the rounded anterior angles of the 

 glabella, the absence of punctations in the marginal furrow, the wider free checks, 

 and the presence of well-marked teeth on the margin of the tail. Of these characters 

 the most reliable in the case of imperfectly-preserved specimens is the shape of the 

 glabella. 



Horizon and Localities. — Upper Lingula Flags: Malvern; Portmadoc ; Moel 

 Gron ; Rhiwfelyn ; YrOrsedd; Arenig ; Aran. 



2. Peltura punctata, Crosfield and Skeat. Plate XI, fig. 13; Plate XII, figs. 



— 6. 



1896. Peltura punctata , Crosfield and Skeat, Quart. Journ. Geol. Soc, vol. Hi, p. 535, pi. xxvi, figs. 

 1—10. 



Head rather more than a semicircle, with rounded genal angles, width about 

 four-thirds the length, surrounded by a narrow raised rim and furrow, with 

 a row of small punctations in the furrow in front of the glabella. Glabella 

 large, forming nearly one-half the total width, quadrate, nearly parallel-sided but 

 with the anterior angles somewhat expanded, truncate in front, reaching the 

 marginal furrow; two pairs of oblique glabellar furrows; neck-furrow well 

 defined. Eye small, placed far forward and very near the anterior angle of the 

 glabella ; ocular ridge faintly indicated. Facial suture apparently marginal in 

 front, running backwards from the anterior margin to the eye, and thence in a 

 gentle curve to the genal angle. Cheeks gently convex, sloping downwards from 

 the axial furrow ; fixed cheeks triangular, at the base rather less than half the 

 width of the glabella ; free cheeks very narrow, crescentic, with the margin pro- 

 longed as a horn in front of the glabella. 



Thorax of twelve segments. Axis considerably wider than the pleurae, occasion- 

 ally with traces of median tubercles on some of the segments. Pleura? bent down- 

 wards at the fulcrum, which is placed about a quarter of the way out, deeply 

 grooved, with a large articular facet; terminations with their front border 

 obliquely rounded off, but ending in short points. 



