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SILURIAN TRILOBITES. 



Distinct at once from II. Knightii by the form of the front margin, which is not 

 sinuous and tricuspid. I do not know the body or the tail, and have much doubt if 

 the species belong to the section Koenigia. It may be referable to Dipleura, and I think 

 it is so. 



Locality. — Upper Ludlow Rock, Ludlow (Mr. W. H. Edgell's cabinet). 



Section — Burmeisteria, Salter. 



HOMALONOTUS ELONGATUS, 71. SJ). PI. X, figS. 1, 2. 



Homalonotus Hersciielii, Phillips. Pal. Foss. fig. 253 (not of Ilurchison), 1841. 

 — sp. Salter. In Morris' Catal., 2nd ed., p. 109, 1854. 



U. caudd 2%-unciali, vix 2 uncias lata, longe trigond, valde convexd fere gibbd. 

 Axis dimidium latitudinis ejjiciens, convexus, et ad ajricem obtusum longum gibbus, 12- 

 annulatus, annulis per dist metis, — primo, secundo, quarto, quinto bitubercidatis. Latera 

 gibba, costis circiter 8 valde obliquis, secundo quinioque tuberculatis, tuberculis magnis. 



Mr. Townshend Hall, junr., of Wadham College, Oxford, has made a fortunate dis- 

 covery, for we have long wanted to know what spinose species of Homalonotus furnished 

 the fragments described from South Devon. The Lower Devonian in every country yet 

 examined shows some species or other of this peculiar group — the H. armatus on the 

 Rhine, the Pradoanus in Spain, the H. Herschelii in South Africa. In South 

 Devon we now have a new form, remarkable even in this elongated genus for the 

 lengthened shape. We have only the tail as yet ; but a diligent search at Meadsfoot 

 Sands will surely discover all the portions of this fine species. And I beg of our friends 

 to make the inquiry. Prof. Phillips has figured some fragments. 



Caudal portion 2| inches long, and only 2 inches wide at the top, and the convexity 

 about \\ inch. Of this form (a frustum of a cone) the axis occupies fully one half the 

 width, and is well marked out, convex in front, and very prominent below. It is annu- 

 lated nearly the whole way down, eleven or twelve rings being distinctly marked, and 

 there is but a small terminal smooth portion. Of these rings, the first, fourth, and fifth 

 bear a pair of approximate spinous tubercles, and the second ring a pair wider apart. 

 The side-ribs are about eight on each side, very oblique, broad, with narrow intervening 

 furrows ; the first and the fourth rib bear each a strong tubercle (probably spinous), 

 directed outwards, and placed less than halfway out. There is a narrow, recurved, lateral 

 margin. The apex of the tail is not recurved or mucronate, but obtuse, the axis being 

 prominent. 



This may be compared with the H. IlerscJielii, Murchison, a common South African 

 species; but ours has a much more elongate and more nodular tail than that fossil. The 



