184 



line running across the neck segment one inch. The margin is prolonged 

 backwards thirteen lines from the neck furrow. The head is rather strongly 

 convex, its elevation at about mid-length of the glabella being about four 

 lines in the specimen, although a little depressed by distortion. The gla- 

 bella is strongly convex, being elevated nearly one line above the level of 

 the cheeks ; it is obtusely rounded in front, and appears to be nearly as 

 broad where a line drawn through the eyes crosses it as it is at the neck 

 furrow, but on this point there is some doubt as the posterior portion is 

 crushed. The neck furrow is well defined across the glabella, and curves 

 a little forward on the median line. The neck segment is well developed. 

 On each side of the base of the glabella, there is an irregularly semi-oval 

 space, the outer margin of which, is abruptly sunk about half a line below 

 the general surface of the cheeks. This space is bordered on its posterior 

 margin by the neck furrow ; on the outer and anterior side, by a nearly 

 vertical elevation of the crust of the cheek, the outline of the space making 

 an obtusely rounded curve on the outside and then turning inward and for- 

 wards to the glabella, which it reaches at an acute angle on a line crossing 

 the eyes. There appears to be a slightly impressed glabellar furrow on each 

 side, which commences at about one line from the neck furrow, at about 

 one-third the width of the glabella from the side of the same, and runs 

 obliquely forwards and outwards, reaching the side at about one line behind 

 the eye. In front of this, there appear to be two small depressions in the 

 side of the glabella, close to the surface of the cheek and opposite the eye. 

 A line drawn across the head through the eyes would cross the glabella at 

 about one third its length from the front. The eyes are small tubercles, 

 scarcely half a line in diameter, and situated about two lines from the side 

 of the glabella. A small thread-like ocular ridge runs from the eye for- 

 " ward, nearly to the front of the glabella, but does not appear to cross the 

 small dorsal furrow which runs round the sides and front. The neck-seg- 

 ment forms a vertical elevation along the posterior margin of % the head, 

 half a line in height, and curving backwards gradually passes into the pos- 

 terior prolongations of the head. These, as far as they can be seen, are 

 nearly vertical, but sloping a little inwards and upwards. 



The surface of the whole head is covered with small irregularly polygonal 

 pits, separated from each other by sharp-edged walls. On the cheeks these 

 pits are, on an average, about one-fourth of a line across, but they vary in 

 size, some of them being much smaller than the others. They seem to be 

 in general a little smaller on the glabella than on the cheeks. Where a 

 portion of the crust is broken away from the front of the head, a cast of 

 the inner surface can be observed. It is covered with small round tubercles, 

 about three in one line. 



This species differs from Harpes antiqwtw, the only species hitherto 



