PHACOPS. 



39 



K*. 7. 



The lobes of the glabella are as follows : — The forehead or frontal lobe transverse, 

 rhombo-trigonal, depressed in the centre, twice and a half as wide as long, rounded- 

 truncate at the upper angles, and only a very little overhanging the position of the eyes. 

 The great lateral " cat's-ear" lobes are right-angled triangles, with the corners rounded 

 off, their larger angle inwards, and only slightly sinuous above, and they occupy in length 

 full half the side of the glabella, and reach more than one third across it, bounded on all 

 sides by very deep furrows. A narrow, triangular space is left between the bases of these 

 lobes for the lower pairs ; the middle lobes are minute, and mere tubercles ; the basal 

 lobes more extended, but still narrower than even the base of the upper lateral lobes, 

 which completely overlap them. The neck-furrow 

 is very strong, and equal across ; the neck-segment 

 of equal width throughout, but its whole breadth 

 is scarcely one half that of the frontal lobe. 



The axal furrows are very deep, and tolerably 

 straight, the cheeks rising very convex from them, 

 bearing the small, strongly lunate eyes.* These 

 have about 100 lenses rather small, and very little 

 prominent, and the pits containing them have on 

 the interior cast an elevated rim or border. The 

 eyes are placed opposite the centre of the frontal 

 lobe, about half way up the cheek, and their own 

 width from the glabella; a deep channel surrounds 

 its base. All the furrows of the head are deep, 

 the marginal one especially so, and the neck- 

 furrow is much curved to follow the descent of the great head-spines. These latter are broad, 

 flat horns, pressed against the body, and extend back a great way, as shown in our woodcut. 



The surface of the head — the glabella especially — is largely tubercular ; and in fig. 20 

 a curious double row of deep puncta runs half way down the forehead-lobe from the emar- 

 ginate front. But this is perhaps not repeated in other specimens. 



The facial suture is not strictly marginal in front, but a little above the margin. 

 Outside the eye it takes a forward curve, and here it lies in an impressed groove. The 

 labrum (fig. 21) has a very broad, arched base, and a blunt-pointed end. The body of 

 the labrum is strongly separated from the wings, and its sides are parallel for a short 

 ■distance, then converge to the rounded obtuse point. There are two deep concentric 

 furrows ; the outer one quite continuous, very strong, and remote from the apex. Above 

 these the organ is convex and roughly tubercular; beyond them it is flat. There is a 

 deep perforation {a) in the broad basal wing, which indicates the place of the ascending 

 process of attachment. t 



* I think Prof. Angelin's figures are not correct ns to the eyes. The cornea must have been thin. 

 T This varies in shape in various species. The form above indicated is a rare one. 



P. macroura, a perfect head in Mr. H. EdgelPs 

 collection : the eye magnified. 



