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Lower latera (figs 10/, a). There are two of these (one much broken) nearly resembling each other: from analogy with the latera of P. unguis y these are probably from the rostral end of the capitulum; they are slightly convex, and approximately form a transversely elongated triangle, with one corner cut off; the two upper sides are slightly unequal in length: umbo of growth at the apex, from this point a narrow well-defined ridge runs obliquely across the valve, to the most protuberant point of the basal margin, which is situated about onefourth of the entire width of valve from one end. These lower latera are wider than, but not so high as the upper latus: seen internally the edges are bevelled, and a very small portion of the apex must have projected freely.