484 GEOLOGICAL SURVEY OF THE TERRITORIES. 



the differences mentioned in its glabella, seem to separate it from that 

 genus. 



In the narrowness of its axis, and the nature of its pleur£e and pleu- 

 ral furrows, it agrees exactly with Conocoryphe ; and even in its cylin- 

 drical glabella, and, indeed, in most of the characters of its head, so far 

 as known, it agrees pretty well with some species of the section Ptyclio- 

 paria, (see Conocor. {Ptychoparia) striatus, Fig. 7, PI. xiv, Barrande's 

 Trilobites of Bohemia.) The comparatively large size of its pygidium, 

 however, and especially its much smaller number of body segments, (9 

 instead of 14,) at once separates it from any section of that genus as now 

 understood. In some of its characters it seems to show affinities to cer- 

 tain types of Ogygia. That is, in the general flatness of its form, its 

 narrow axis, and the form and furrows of its glabella ; but it differs in 

 having nine instead of only eight body segments ; while its pleural 

 furrows are of a different type, and its eyes are smaller, much less arcuate, 

 and more remote from the glabella. Its facial sutures, although not 

 clearly seen in any of the specimens, in front of the eyes, were probably, 

 judging from some indications, not so diverging anteriorly. 



If further comijarisons should show it to be generically, or subgener- 

 ically, distinct from all of the groups mentioned, as I believe it to be, it 

 may be designated by the name Bathyurisous. 



The specific name is given in honor of Dr. F. V. Hayden. 



Locality and position, — East side of Gallatin Eiver, above Gallatin 

 City, Montana. Potsdam or Primordial group. 



Bathyurellus (Asaphiscus) Bradleyi, Meek. 



The best specimens of this species I have seen, consist of the central 

 parts of the cephalic shield, separated from the movable cheeks. These 

 parts may be described as follows : 



Glabella moderately and evenly convex, nearly oblong or truucato- 

 subconical in outline, being a little narrower at the front than behind, 

 and truncated anteriorly, with the anterior lateral angles rounded ; 

 exclusive of the neck segment, one-sixth to one-seventh of its length 

 longer than wide ; sides slightly convex in outline or nearly straight, 

 and converging gently forward from near the middle, well but not 

 deeply defined by the dorsal furrows, which are narrow, and continue 

 around the front ; lateral furrows wanting, or apparently sometimes 

 very obscurely indicated by two or three pairs of extremely faint 

 indentations. Neck furrows narrow, but distinct, extending entirely 

 across, and continued more strongly defined across the posterior mar- 

 gins of the cheeks. Neck segment rather wide in its antero-posterior 

 diameter, and flattened in this direction, but transversely arched so as 

 to be nearly as high at its middle as the glabella. Anterior extension 

 or limb, moderately produced, or equaling one-third the length of the 

 glabella, (exclusive of the neck segment,) sloping gently forward from 

 the anterior end of the glabella for about half way to the front, where 

 there is thus formed a transverse furrow from which it rises obliquely 

 forward in the form of a nearly flat marginal rim. Palpebral lobes 

 comparatively large, or constituting all there is of the fixed cheeks, 

 lunate, or sub-semicircular in form, depressed below the horizon of the 

 glabella, from which they are only separated by the dorsal furrows, 

 each occupied by a lunate slightly convex central portion, (which might 

 be viewed as minute fixed cheeks,) separated from the outer margin by 

 a shallow furrow. Eyes, as determined by the palpebral lobes, about 

 four-sevenths as long as the glabella, exclusive of the neck segment, 



