[matthbwJ studies ON CAMBRIAN FAUNAS 177 



like it, has a punctate surface. It shows no furrow on the glabella, thus 

 ditfering from A. ceticephalus var. carinatus. It differs from A. Roberti 

 (see below) in its narrower marginal fold, both before and behind the 

 head-shield. 



AORAULOS ROBERT!, U. Sp. (PI. II., HgS. 4 (I and h.') 



Only the middle piece of the head is known ; this is subtrapezoidal 

 in form. The anterior marginal fold is flat, wide and crescentic, and the 

 anterior furrow in most examples fades out at the axial line. The front 

 area of the cheeks is wide and rather flat ; this and the fold are together 

 equal to the width of the glabella at the front third. The glabella is 

 conical, somewhat longer than wide, and smooth ; and the posterior furrow 

 is faintly distinguishable. The occipital furrow is distinct, but shallow. 

 The occipital ring is rather narrow, and terminates in a slender spine 

 about as long as the ring is wide, and directed upward. The dorsal 

 furrow is distinctly but moderately impressed. The flxed cheeks are 

 narrow, the width of the cheek and eyelobe being equal to the length of 

 the head between the glabella and the front margin. The ocular fillet is 

 faintly discernible, and the ocular lobe is narrower and low. The pos- 

 terior marginal furrow is distinct, but not deep, and its fold is strongly 

 angulated in the middle. The facial suture is nearlj^ straight, and 

 parallel to the side of the glabella. 



Sculpture. — The surface of the shield is minutely punctate. 



Size. — Length of the head, exclusive of the spine, 9 mm. ; length of 

 the spine, 1 mm. ; width of the middle piece of the head, 9 mm. 



Horizon. — Founa with the preceding species. 



This species resembles A. Whttjieldianus of the horizon, Div. 1 c, 1, 

 but ditters in the wider frontal area of the cheeks, the more conical 

 glabella, the narrower occipital ring, and the flatter contour of the shield. 

 Anomocare (f) par v urn of Walcott might be a larval or dwarfed form of 

 this species.^ A. Robert' ditt'ers from A. ceticephalus, Barr., in the more 

 direct posterior extension of the dorsal suture, the wide angulated posterior 

 fold and the form of the occipital ring and spine.^ From A. difformis, 

 Ang., it diflers in the more conical glabella, and the absence of a trans- 

 verse furrow in front of the glabella.* 



This species is named for Mr. Eobert Matthew, who placed his yacht 

 at the disposal of a committee of the Natural History Society of New 

 Brunswick for the investigation of this fauna and others. 



1 Fauna of the Olenellus Zone, p. 209, pi. xxv., fig 1. 

 -Barrande and de Verneuil, 1. c, p. .526, pi. vi., figs. 13—17. 

 •On Paradoxides skifrene v. Krekling, p. 58, tab. iv., figa. 1 to 8. 



