F. R. Cou-per Reed — New Bala Trilobites. 53 



close under the great frontal lobe, which has its posterior border 

 notched by the first pair of furrows. The posterior pair of lobes, 

 which are slightly smaller and less distinct than the anterior, are 

 situated about half-way between the neck lobe and the anterior pair. 



The neck lobe is very narrow, and is only marked off from the 

 rest of the glabella by a shallow, transverse groove. Behind the 

 cheeks the neck segment is distinguishable as a gi'adual elevation 

 of the posterior margin of the neck furrow, which has a steep 

 anterior slope. But as the neck segment is followed towards the 

 outer angle of the cheeks it assumes greater prominence, broadens 

 and becomes a rounded distinct ridge usurping two-thirds of the 

 width of the neck furrow. 



The triangular cheeks are much inflated and rise abruptly from 

 this furrow to rather more than half the height of the frontal lobe, 

 from which they are separated by a deep axal furrow. The axal 

 furrow is in this part narrower than it is posteriorly, where it 

 widens out and becomes less deep, so as almost to attain the width 

 of the glabella stalk. This widening of the furrow is due to the 

 sudden contraction of the glabella behind the frontal lobe, and to 

 the inner side of the cheek making nearly a right angle with the 

 posterior edge of the head-shield instead of following the outline 

 of the glabella. The cheeks do not overhang the fringe, but rise 

 from its inner border with a pronounced convexity; the inner and 

 posterior borders of the cheeks form steejD and abrupt slopes. 



A tubercle similar to that on the frontal lobe is situated on the 

 most elevated point of each cheek. A fine reticulated kind of 

 sculpture, with elongated meshes, ornaments the cheeks and glabella. 

 There is no facial suture or " eye-line " visible. 



The fringe surrounding the front and sides of the head-shield 

 is parabolic in outline in the male, but semicircular in tbe female, 

 as already mentioned. It is of constant width throughout, except 

 in front, where the glabella invades it to half its width, and at 

 the posterior angles, where it slightly expands. Its average width 

 is a little less than one-third the length of the glabella. The upper 

 surface of the fringe, which is gently concave, with a rounded edge, 

 bears 20-26 radially-elongated deep sulci, of which the anterior are 

 rather broader and more open than the posterior. Along the bottom 

 of the 14-18 median sulci lie three conical pits (PI. III. Fig. 6) : 

 the anterior one is smaller than the other two and does not com- 

 municate with the lower surface of the fringe. The two other 

 larger pits, of which the posterior is of greater size, communicate 

 with the lower surface by means of a minute pore at their base — the 

 apex of the cone — which leads into a similarly arranged and corre- 

 sponding pair of inverted conical pits opening on the under surface 

 of the fringe. Whereas the anterior pit is only present in the 

 median 14-18 sulci, the two larger pits with their corresponding 

 pair of lower-surface pits are present in all the sulci of the fringe. 

 In the last four or five sulci on each side the two pits on the upper 

 surface approach more closely to each other until in the last two or 

 three sulci they have actually fused more or less into one. In the 



