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SILURIAN TRILOBITES. 



Genus — Staurocephalus, Barrandc, 1846. 



Head cruciform, with long clavate glabella, greatly swelled in front into a hemispheric 

 lobe ; — the base narrow, cylindric, with two pairs of lateral furrows. Cheeks convex, with 

 pedunculate eyes, and serrate edges. Facial suture ending on the external margin. 

 Body-rings ten, without pleural grooves, pointed. Tail of few segments, the apices of 

 the pleurae free. — Barrande. 



Staurocephalus Murchisoni, Barrande. 



Staurocephalus Murchisoni. 



PI. VII, figs. 13—20. 



Barrande. Prodrom. Sil. Syst. Boheme, p. 53, 1 84 f> . 



„ Syst. Sil. Bolieme, pi. xliii, fig. 28 — 32 

 1852. 



M'Coy. Synopsis Woodw. Mus., pi. i f, fig. 15, 

 1855. 



Salter. Morris's Catal., 2nd. ed.p. 115, 1854. 



Id. Siluria, 2nd ed. p. 540, 1859. 



Id. Decade 11. Geol. Surv., pi. 5, fig. 1-5, 1865. 



S. ovatus, tuberculosus, oculis remotiusculis, margine genaruni spinoso. Cauda quadrata, 

 pleuris sex, omnibus tfqualibus retrorsis parallelis, hand divaricatis. 



One of the most curious, if not one of the most conspicuous, of our British species. 

 The globular head, or rather glabella, set on its narrow stalk-like base ; the gibbous 

 cheeks, projecting eyes, serrate border, and spiny comb-like pleurae and tail — combine to 

 give a most unusual and extravagant appearance to the fossil. It is seldom found 

 perfect; but the skill of the Dudley naturalists has long been exercised on it, and speci- 

 mens are now to be found in several cabinets. Mr. Hollier's and Mr. Ketley's very 

 fine specimens are the principal ones figured. Our fig. 18 is from the Museum of 

 Practical Geology : it was formerly in Mr. E. Davis's collection, and is from Presteign. 



About an inch long, of which the gibbous head occupies more than two fifths. This 

 is longer than broad, roughly triangular in general outline, but not truly so. It appears 

 rather four-lobed, or like the heraldic "fleur-de-lis," the truly globular front occupying 

 more than half the length of the glabella, and being at least three times as wide as its 

 semicylindrical base, from which it is abruptly cut off by a transverse furrow ; the base 

 is marked by two distinct lateral lobes, besides the neck-furrow. The cheeks reach 

 forward about half way up this globular portion ; and the central part is unusually 

 raised, so as nearly to be on a level with the glabella. The cylindrical eyes are on the 

 most convex part of the cheeks, and are directed outwards, scarcely forwards. The 

 margin is distinct in front of the head, has a very narrow prominent ridge, and furnished 



