Marylaxd Geological Survey 491 



lobed; the cheeks sloping abruptly from the eyes to the outer margin: 

 posterior angles subacute (perhaps prolonged into spines in entire speci- 

 mens) ; eyes prominent. Occipital annulation prominent; the furrow 

 strong, and marked below each posterior angle of the glabella by a small 

 tubercle. Thorax consisting of nine or ten articulations (the specimen 

 being too imperfect for actual determination). The axis is very promi- 

 nent, semicylindrical, and the lateral lobes nearly fiat for a little distance 

 from their origin, and then bending abruptly downwards. Pygidium semi- 

 circular: axis very prominent, marked (in the cast) by eight annulations; 

 lateral lobes marked by four or five ribs. Surface granulate; the anterior 

 border, and articulating surfaces of the axis striate: exfoliated surfaces 

 striate." Hall, 1859. 



Occurrence. — Helderberg Forjiation, Xew Scotland Member. 

 Corriganville. 



Collection. — American Museum of Natural History. 



[Ohern.] 

 Genus CORDANIA Clarke 

 CoRDAXiA CYCLURUS (Hall and Chirke) 

 Plate LXXXIX, Figs. 5, G 



Phacthonides cycluriis Hall and Clarke, 1888, Nat. Hist. N. Y., Pal., vol. vii, 

 p. 137, pi. xxiv, figs. 26-28; pi. xxv, fig. 11. 



Description. — " Cephalon. The i:itra-siitural portion, which is the only 

 part known, indicates a semicircular outline for the head ; frontal and 

 lateral areas depressed and concave ; frontal margin elevated, rising to 

 the height of the glabella, broad, thickened and rounded. Palpebral lobes 

 conspicuous. Glabella subpyriform, convex, slightly flattened above, 

 bounded by a sulcus which is strong at the side and obsolete in front. 

 Baso-lateral lobes strong; antero-lateral impressions well marked. Cheeks 

 appressed and elevated along the lateral margins of the glabella. Thorax 

 not observed. Pygidium semicircular; length to width as 1 to 3. Axis 

 prominent, elevated and longitudinally arched ; width less than one-third 

 that of the shield, rapidly tapering to an apex just within the posterior 

 border; composed of nine annulations which are transverse, rounded and 



