28 DEVONIAN FAUNA. 



border and rounded in front, with four furrows ; the first frontal furrow short, 

 horizontal, and indistinct ; the second longer and slightly oblique ; the occular 

 furrow more oblique, and reaching almost to the central line ; the basal furrow 

 still more distinct and oblique, and bifurcating shortly before the central line, which 

 it almost reaches ; the lobes, separated by the furrows, gently convex. Glabella 

 bounded by a shallow furrow which is arched to include the eye. Cheeks long 

 and convex, beginning in front of the glabella and extending back about a quarter 

 of their length behind the basal lobe, bounded behind by an oblique groove. Eyes 

 rather small, long, rounded, and smooth, situated close to the glabella and 

 beginning at the frontal groove. Facial suture cutting the border very obliquely, 

 turning suddenly in the marginal groove at a level with the front of the glabella, 

 coming inwards in a convex curve to the front of the eye, forming a shallow 

 eye-lobe almost parallel to the sides of the glabella, and cutting the hind margin 

 of the cheek obliquely almost close to the neck-lobe. 



Tail elongate, slightly convex ; in outline oblique in front, rounded behind. 

 Border flat, slightly sloping, wide behind. Axis long, straight, conical, reaching 

 almost close to the border with an indistinct prolongation behind, bounded by a 

 linear furrow or angle ; bearing eighteen or nineteen narrow, decreasing rings, 

 distinct in front, becoming almost imperceptible near the end. Limb convex, 

 bearing about thirteen oblique arching ribs, slightly grooved near the axis, and 

 ending suddenly at the border. Border flanked with minute oblique stria? in the 

 upper part, which possibly become minute marginal spines further down. 



Size of Head. — 15 mm. long, 22 mm. wide, and 6 mm. deep. 



Size of Tail. — 17 mm. long, 20 mm. wide, 6 mm. deep. 



Locality. — Chircombe Bridge, in black limestone. There are seventeen speci- 

 mens of the tail in Mr. Vicary's Collection, two in the British Museum, five in 

 Museum of Practical Geology, three in the Woodwardian Museum and ten in the 

 Torquay Museum. The only specimens of the head I know are one in Mr. Vicary's 

 Collection, and one in the Museum of Practical Geology. 



Remarks. — These fossils occur in a beautiful state of preservation, and are of 

 a glossy-black colour, slightly tinged with translucent red. The external layer of 

 the test is minutely pitted on the head and the margin of the tail. On the parts 

 of the glabella from which it is removed, the lobes and furrows seem more 

 distinctly marked than where it is remaining. The strige on the border of the tail 

 are very minute, and have the appearance of small hairs. They can only be seen 

 under a lens. 



Kayser's type species Dechenella Verneuili 1 (Barr.) differs from our English form 

 in its shorter head, longer glabella, and more arched and angular facial suture. 

 There is a more angular prominence on the cheek near the genal angle, and the axis 



1 1852, Barr., ' Syst. Sil. Bohem.,' p. 478. 



