niCKS — MENKTIAN POSSILS. 177 



ERiifNTS VENUiosA, Salter. PI. VI. figs. 1-6. 

 Brit. Assoc. Report, 1865. 



Ovate in form, being widest in front, and surface depressed. The 

 largest specimens indicate a fossil at least 3| inches long. 



Head semicircular, margined all round, but with no posterior 

 spines, wider than the body. Glabella small, occupying only about 

 two thirds of the length and about one fifth of the width of the head, 

 pyramidal in shape, slightly raised, and indented by three pairs of 

 furrows ; the hinder ones reaching backwards nearly to the neck-lobe, 

 and marking off triangular lobes on^each side. 



There are no distinctly marked eyes or facial sutures ; but a 

 tolerably strongly raised ridge strikes off on each side from opposite 

 the upper glabellar lobes towards the posterior angles, reaching 

 nearly | of the distance across. From these ridges lines strike off 

 in each direction, especially forwards, dividing and subdividing in 

 their course, and giving a veined character to the whole surface. 



Thorax composed of 24 rings ; axis narrow, convex, and tapering 

 towards the tail ; pleurae compressed, grooved, and, including the 

 spines, more than twice as long as the rings of the axis ; spines 

 bent backwards from the fulcrum, at which part the surface becomes 

 suddenly raised into a sharp transverse ridge. 



The tail is semicircular, and has a tolerably strong axis, composed 

 of four segments. The lateral lobes are marked by four moderately 

 well defined ribs. 



Loccditif. —MeneYian group : St. David's, South Wales ; and "Water- 

 fall Yalley, near Maentwrog, North Wales. 



Caeattsia, gen. nov. 



Geti. char. Ovate in form and moderately convex. The head oc- 

 cupies about two fifths of the whole length, is more convex than the 

 body, margined, and, without the posterior spines, nearly semicircular 

 in form. The spines extend backwards to about a third of the length 

 of the body, but point outwards, so that at their extremities they arc 

 separated from the body by a space equal to about half the length of 

 the opposite pleurae. The glabella occupies less than a third of the 

 width and about two fifths of the length of the head ; it is more con- 

 vex than the cheeks, and is separated from them by deep lateral 

 furrows, but indistinctly so anteriorly. Two furrows indent the 

 glabella on each side. There is no appearance of eyes or facial 

 sutures ; but, as in Erinnys, a ridge extends across from the glabella 

 towards the outer margin, giving off branches in its course, which 

 again subdivide, until a veined appearance is given to the whole 

 surface. In the single specimen found 15 rings of the thorax only 

 are preserved; and from general appearance this would seem to be 

 near the full number. The axis is strongly raised, and less in width 

 than the lateral lobes. The pleurae are deeply grooved, and produced 

 into tolerably long spines, which are longer in the upper and middle 

 p] euros than in the lower ones. 



Tail? 



This genus resembles in some respects Hohceijludlna, and in others 



