﻿AMPHION. 



81 



It was a proof of the late General Portlock's scientific acumen to have decided this to 

 be an Aiiiphion, a genus, be it remembered, never recognised in Britain before his work 

 appeared ; for assuredly the characters of the head are unlike those of the typical species, 

 and yet there is no manner of doubt that we must admit it, and enlarge the generic cha- 

 racter so to do. The forehead-lobe is much wider in this than in the other species, 

 as our woodcut will show. (Fig. 17.) 



The species probably grew three inches long, as indicated 

 by fig. 30. The head is transverse, semicircular, or nearly 

 so ; the glabella, which is moderately convex, occupying fully 

 one third, and regularly, but very slightly, tapering back- 

 wards to the small neck -segment. The furrows are three 

 on each side, very short, and somewhat radiating, en- 

 closing a linear basal lobe, a clavate middle one opposite the eye, and a subrectangular 

 upper lobe, between which and the very short, wide, and transverse forehead-lobe is only 

 a short, straight furrow ; but beneath this it is continued as a faint curved depression 

 (not shown in our figure), so as to follow the direction of the middle or ocular furrow. 

 The forehead-lobe (and this is unusual for the genus) is as wide as the rest, and is a 

 narrow linear segment. It has no central furrow, such as exists in A. Fischeri, nor any 

 crenulate border in front ; indeed, the front margin must have been very narrow, as our 

 figure (woodcut 17) indicates. 



The cheeks are triangular and gently convex, strongly and rather deeply marginal, the 

 margin being not so broad externally as in A. Fischeri, and the cheek consequently more 

 triangular and less oblong. The eye is placed far inwards for the genus, and only 

 one third up the cheek. We have not the actual eye. It was small, but is not preserved 

 in our specimen. The facial suture curves largely out and upward beyond the eye, and 

 cuts the obtuse head-angles. 



As the glabella is more convex than usual in the genus, so is the axis of the thorax 

 which follows it, and which is not so wide as the sides, but wider in proportion than other 

 species. The pleurae are each convex, especially within (in the cast), and have the fulcral 

 point at one third, whence they bend backward and curve downward. No pleural groove 

 shows on the exterior surface, but within the crust the furrow is visible on the anterior 

 edge of the segment. 1 The extremities are curved, and apparently rounded, but this 

 last may be deceptive. 



The tail is remarkable, and in our largest specimen (fig. 30) shows well the characters 

 which separate it from A. Fischeri. Its parabolic flattened axis, divided into five rings, 

 reaches barely more than half the length, divided by only faint axal furrows from the five 

 side pleurae, of which four are well distinct on each side, and have a sublinear but some- 



1 This is usual in all genera with ungrooved pleurae, and hence the distinction of those groups which 

 have " plevre a sillon," from those which have " plevre a bourrelet " is an artificial one. Cheirurus and 

 Spliaerexochus show the intermediate character. 

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