Page:Quarterly Journal of the Geological Society of London, vol. 28.djvu/215

 the tips. Axis trilobed, the central lobe being largest and pyramidal in shape. The two lateral lobes triangular in shape.

Tail of the same shape as the head, but more strongly margined. The axis is large, and occupies more than a third of the width, reaches backwards to within a short space of the posterior margin, and is indented by three furrows on each side, each running obliquely backwards from the centre, which is somewhat raised. Locality. — Menevian group : St. David's ; and near Dolgelly, North Wales.

Agnostus Eskriggei, Hicks. Pl. V. fig. 7.

About 1/6 of an inch long. Head and tail each nearly circular in form, highly convex, and with a smooth surface. Glabella indistinctly marked by short lateral furrows.

Thorax compressed, not so wide as the head.

The axis of the tail is equal to about half of the width, nearly circular in form, and exhibits no distinct furrows.

Locality. — Menevian group : St. David's ; and near Dolgelly, North Wales.

Agnostus scutalis, Salter. P1. V. figs. 9-14.

Brit. Assoc. Report, 1865.

This is the most plentiful species found in the Menevian group. It seldom exceeds 1/2 an inch in length, though some of the specimens are lengthened by pressure to rather over 1/2 an inch. The general form of the head and tail about two thirds of an oval, highly convex and strongly trilobed, also strongly marginate. Glabella long and narrow, occupying rather less than a third of the width of the head, and tapering slightly ; it is divided by a transverse furrow into two lobes — an anterior of spheroidal shape, and a posterior elongated lobe which supports a tolerably strongly marked tubercle ; a pair of triangular lobes lie at the base of the glabella. The cheeks are covered with small tubercles.

Joints of the thorax strongly raised, axis trilobed, and pleurae deeply grooved.

Tail nearly of the same shape as the head ; axis equal to about a third of the width. The axis is of about equal width for the upper half, and then tapers to a sharp point from which a groove runs to the posterior margin ; it is divided into three lobes, the anterior stretching as a narrow band across, the second transversely lozenge-shaped, with a centrally raised tubercle, and the hinder one pyramidal. The lateral lobes of the tail are disconnected by means of the terminal furrow, and like the cheeks are covered with tubercles.

Locality. — Menevian group : St. David's and near Maentwrog and Dolgelly.

Agnostus scarabaeoides, Salter. P1. V. fig. 8.

It is 1 inch long, Head and tail rounded to rather less than two thirds of a circle, and surrounded by a narrow margin ; surface depressed; head rather wider than long. Glabella pyramidal in