Anopolenus impar, nov. sp. Pl. VII. figs. 1-7.
In none of the specimens found were the free cheeks attached to the head; but the position of the sutures indicates that, when present, the head must have been semicircular in form, with two tolerably long spines reaching backwards from the posterior angles. The glabella reaches to the margin in front, is rounded anteriorly, and is widest at the base of the frontal lobes. It occupies more than a third of the width of the head, and is raised somewhat above the level of the cheeks, from which it is separated by tolerably deep lateral furrows. It is grooved by one complete and two incomplete lateral furrows, and one pair of small anterior furrows. The hinder furrow and the neck-furrow are strong and remote from one another. The inner cheeks are narrow, and bounded on the outside along their whole length by the eye-lobe, which is wide and flexuous, and on the inner side for the lower two thirds by the cheek-lobes, which are well marked in some of the specimens, The outer cheeks are narrow, and have long posterior spines attached. The thorax consists of 14 segments ; axis wide and tapering. The anterior pleurae are shorter than the rings of the axis, and are scarcely, if at all, spinous at the ends. The three hindmost pleurae, however, have very long spines, which bend backwards, and reach on each side beyond the extremity of the pygidium.
The tail consists of a wide, raised and tapering axis of four or five segments, extending nearly to the posterior margin, and of a furrowed, strongly margined limb, serrated on the outer edge. This species is distinguished from Anopolenus Salteri by having wide, flexuous eye-lobes, very narrow inner cheeks, a rounder anterior border to the glabella, wider axis to the thorax, and a stronger and longer axis to the tail. Its narrow inner cheeks and wide flexuous eyes distinguish it also from Anopolenus Henrici.
Locality. — Menevian group : St. David's ; and Maentwrog, North Wales.
Anopolenus Salteri, Hicks. Pl. VII. figs. 8-11. Quart. Journ. Geol. Soc. vol. xxi. p. 478.
In the Quart. Journ. Geol. Soc. vol. xxi. a detailed description of this species is given, along with a restored figure compiled from the fragments then discovered. Since then, however, other and more perfect specimens have been found, which show that, though for the most part the figure there given is correct, yet a few points need alteration. The specimens now figured indicate that the glabella was narrower, and tapered sharply anteriorly — that the free cheeks were not cut off abruptly, but continued in a line with the posterior margin, as in A. impar — and that the axis of the tail was longer.
Locality. — Menevian group : St. David's.
Cyrotheca hamula, Hicks. Pl. VII. fig. 14.
A curved Pteropodous shell, nearly 1/2 inch long and 1/6 of an inch wide at the upper part, and gradually tapering backwards. It
