A monograph of British Trilobites - Tapa blanda

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1883 Excerpt: ...closely placed, but they cover the whole surface. The shape of the tail is truly triangular, as wide as long, contracted near the apex, and then pointed, the tip somewhat recurved.1 The axis is rather narrow, and not much distinguished from the sides, the furrows being quite continuous across. There are eight of them, the upper not stronger than the rest; and all are deep furrows, only rather less broad than the intervening ridges. They arch across the axis, which is only slightly convex, and pass direct across the sides, which are gibbous externally, but rather flattened above. The eight furrows abruptly cease at rather beyond halfway down the tail: on the sides they cease entirely; on the axis there are one or two faint ribs beyond them. The incurved under margin of the tail is very remarkable. It is sharply incurved, strongly concave, and roughly granular, and there is besides a strong lateral contraction about halfway down the tail (see fig. 9). Localities.--Abundant in the Upper Ludlow Rocks of Shropshire, and all the border counties; also of Radnorshire, and other places in South Wales; Llangollen, North Wales; Westmoreland, near Kendal, abundant; and under the name of H. rhinotropis it occurs in Gothland. Dr. Honeyman has found it at Arisaig, Nova Scotia. H. ludensis, of Murchison, is now well understood to be a synonym;s but nevertheless there are two species in the Ludlow rocks, even in England. And to preserve this old name, I beg to apply it to the very unpretending looking head, fig. 1 (lent to me by Mr. H. W. Edgell, jun.). That species has not the tricuspid front of H. Knightii, but a smooth regular contour to the margin; and is, indeed, more nearly hke the H. bisulcatus; but I cannot be sure to what sub-genus it should be referred--possibly t...