DESCRIPTIONS OF NEW SPECIES OF FOSSILS." 
By R. P. Wuarrrrecp. 
Genus CREPICEPHALUS, Owen. 
OREPICEPHALUS (LOGANELLUS) MONTANENSIS, n. sp. 
Plate 1, figs. 1 and 2. 
Glabella and fixed cheeks, when united, subquadrangular in outline, contracted across the eyes, 
and abruptly expanding in front. Glabella narrowly conical, moderately tapering anterior] y, some- 
what squarely truncate in front, strongly elevated, and gibbous in the middle and along-the central 
line, marked by three pairs of lateral furrows, which are directed obliquely backward at their inner 
ends; anterior pair very short, and placed near the anterior end of the glabella. Occipital furrow 
only moderately strong. Fixed cheek rather narrow, not exceeding one-third the width of the glabella. 
Eye-lobes proportionally large. Frontal limb long, equaling half the length of the glabella. No 
perceptible anterior rim can be detected on the part preserved. Ocular ridges distinct. Posterior 
lateral limbs long and narrow, their lateral extension about equal to the width of the glabella. 
The species is kuown only by the glabella and fixed cheeks, the latter imperfect; but the form 
is so unlike any other of the genus described that there can be no difficulty in recognizing it. ‘The 
extreme elevation of the glabella is a marked feature. 
Locality and formation—In limestone of the Potsdam Group overlying quartzite near Camp 
Baker, Montana. 
Genus ARIONELLUS, Barrande. 
ARIONELLUS TRIPUNCTATUS, 0. sp. 
Plate 1, figs. 3-5. 
Specimens consisting only of the central parts of the head and separated movable cheeks. 
Glabella conical, the height above the occipital furrow equal to the greatest width at the fur- 
row; anterior end rounded, as wide as two-thirds of the length above the occipital furrow; margins 
defined by strong, well-defined dorsal furrows; surface moderately convex, and very faintly angular 
along the median line; marked by three pairs of very faiut lateral furrows, which are directed 
obliquely backward at their inner ends; occipital furrow deep, extending entirely across the base 
of the head; occipital ring moderately strong, and projecting backward in a central spine of unde- 
termined length. 
Fixed cheeks narrow and prominent, but rapidly sloping to the margins in front of the small, 
prominent and somewhat pointed palpebral lobes. Frontal limb short, rapidly narrowing at the 
sides, in front of the eyes, to the anterior furrow, which is deep and strong; anterior to the furrow 
the limb is suddenly contracted and subangular in the middle; bottom of the furrow marked be- 
tween the sutural margins by three deep well-marked pits. Postero: -lateral limbs narrow at their 
origin, beyond which they are unknown. 
*The types of all the species here described are in the Peabody Museum of Yale College, New Haven, Conn. 
