Page:Quarterly Journal of the Geological Society of London, vol. 28.djvu/217

 ERINNYS VENULOSA, Salter. Pl. 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 3-1/2 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 2/3 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.

Locality. —Menevian group : St. David's, South Wales ; and "Waterfall Valley, near Maentwrog, North Wales.

Carausia, gen. nov.

Gen. char. Ovate in form and moderately convex. The head occupies 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 are 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 convex 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 pleurae than in the lower ones.

Tail?

This genus resembles in some respects Holocephalina, and in others