20 TRILOBITES OF GIRVAN. 



as long, curvature rather flattened anteriorly; posterior margin concave owing to 

 slight bending back of lateral angles of middle-shield. Glabella oval, about one third 

 the width of head-shield, with subpyriform swollen anterior half and depressed pos- 

 terior portion. Frontal lobe strongly elevated and swollen, with prominent median 

 tubercle near anterior end; neck depressed and bordered laterally by pair of longi- 

 tudinal elongated lobes imperfectly marked off by oblique isolated deep furrows 

 ending in pits and almost parallel with the axial furrows, but not connected with 

 them or with the occipital furrow. A pair of shorter parallel furrows is situated 

 further forwards and a little more inwards on the posterior slopes of the frontal lobe of 

 the glabella. Base of neck somewhat elevated between posterior ends of longitudinal 

 lateral lobes. Occipital furrow wide, shallow. Occipital ring rounded, projects 

 backwards. Surface of glabella very finely granulated. Fixed cheeks broad, 

 feebly convex, reach up to front end of glabella, and are united in front of it 

 by narrow band, not overhung by frontal lobe. Surface of fixed cheeks marked 

 by 9 — 10 fine radiating lines, arising halfway up side of frontal lobe and running 

 obliquely backwards or outwards ; two or three are usually larger and more distinct 

 than the rest. Facial suture oblique, cutting front margin just outside frontal lobe of 

 glabella, and running backwards to posterior border at about -15°. Free cheeks 

 unknown. 



Thorax of six segments. Axis convex, slightly tapering, more than half as wide 

 as pleurse ; axial rings have pair of lateral nodules. Pleura? straight, horizontal, 

 broad, grooved along their length. 



Pygidium flattened, broadly triangular, about twice as wide as long. Axis 

 long, narrow, reaching posterior border, rapidly tapering, conical, segmented for 

 whole length, first 8 — 10 segments distinct, with obscure lateral nodules. Lateral 

 lobes flattened, wholly segmented by pleurae which reach border and have a faint 

 median longitudinal ridge, but only the first or 7 are distinct. First half -pleura 

 marked off by specially strong oblique furrow. Border broad, steeply bevelled, 

 concentrically lineated with interspaces pitted. 



Dimensions (of types). — 

 I. Length of head ..... 15'0 mm. 

 Width of „ at base without free cheeks . . 38*0 „ 



II. Width of thorax ..... 20"0 „ 



,, of axis ..... 5*0 ,, 



" °^ pygidium .... 16*5 ,, 



Length of ,, . . . . 7*5 „ 



Remarhs. — The pygidium in Mrs. Gray's collection from Balclatchie figured by 

 Nicholson and Ktlieridgc (Inc. rit.) as Asaphus, sp., probably belongs to this species. 

 There is a distinct bevelled border visible on one side; the pleura? are straight and 

 similar to those in typical examples of Anvpyx homei ; the axis (so far as its state 

 of preservation permits to be seen) is similar, and the anterior border is straight 



