346 SYSTEMATIC PALEONTOLOGY 



Description. Entire cephalon unknown. Free cheek broad, flat, tri- 

 angular in outline, bearing a long spine at the genal angle. Glabella flat 

 with a narrow depressed border in front and scarcely any traces of dorsal 

 furrows. Eyes prominent with their longest diameter 5 mm. and between 

 them a minute pustule. The pygidium is uniformly convex with a 

 narrow, depressed border, and is semicircular in outline. Its axial lobe is 

 narrow and improminent, with traces of three or four rings at the anterior 

 end. Size of the pygidium varies from 10 mm. in width and 7 mm. in 

 length to 50 mm. by 40 mm. Hypostoma quadrangular. 



This species much resembles Hemigyraspis collieana Kaymond with 

 fragments of which it is associated in Maryland, but its cephalon is longer 

 and narrower and the axial lobe of the pygidium not so prominent. 



Occurrence. BEEKMANTOWN LIMESTONE (Stonehenge member). 

 Vicinity of Hagerstown, Maryland. Tribes Hill limestone of New York 

 and upper part of Kittatinny limestone of New Jersey. 



Collection. U. S. National Museum. 



Genus HEMIGYRASPIS Raymond 

 HEMIGYRASPIS COLLIEANA Eaymond 



Plate XXXII, Figs. 11-15 



Asaphus marginalis Collie (not Hall), 1903, Bull. Geol. Soc. Amer., vol. xiv, 



p. 413. 

 Hemigyraspis collieana Raymond, 1910, Ann. Carnegie Mus., vol. vii, p. 41, 



pi. xiv, figs. 9-13. 



Description. " Cephalon short and wide, glabella smooth, not out- 

 lined, no glabellar furrows. Neck-furrow shallow, hardly visible. Eyes 

 nearly halfway to the front of the cephalon, large, very far apart. Between 

 the eyes is a small median tubercle. Free cheeks short, wide, with long 

 narrow spines at the genal angles. The anterior limb of the facial suture 

 meets the frontal margin in front of the eye. There is a narrow depressed 

 border on the front of the cranidium. 



"Axial lobe of thorax one-third the total width; pleura grooved. 

 Pygidium short, wide, semicircular in outline. Axial lobe narrow, rather 

 prominent, showing traces of two or three rings. Pleural lobes convex, 



