270 PROCEEDINGS OF THE ACADEMY OP 



We know of no species with which it could be, for a moment, confounded. 

 With the exception of the above mentioned peculiarities of the eyes, it agrees 

 well with the characters of Griffithides, and doubtless must be called Griffi- 

 t hides PoTtlockii, if that group is to be retained as a distinct genus. 



Named iu honor of Col. J. E. Portlock, of the Royal Ordinance Survey, of 

 Ireland, and author of the genus. 



Locality and position. Warsaw, Illinois ; Keokuk Limestone, of Subcarbo- 

 niferous series. 



Phillipsia (Griffithides) scitula, M. & W. 



Small, entire outline nearly elliptical. Cephalic shield semielliptic, very 

 convex, about one-third its breadth wider than long, rounded anteriorly, and 

 nearly straight, or more or less concave in outline behind, with posterior la- 

 teral angles produced backwards into rather stout, carinated, pointed spines, 

 which extend as far back as the fifth thoracic segment. Glabella broadly 

 rounded and sloping in front, where it is destitute of a projecting marginal 

 rim ; distinctly contracted posteriorly, in which region it is most elevated ; 

 separated from the cheeks on each side by its much greater convexity, and a 

 shallow furrow, which becomes obsolete around the front ; posterior lateral 

 lobes comparatively large, subtrigonal, very oblique, depressed and isolated 

 by the strongly defined lateral furrows in front of them being so very oblique, 

 and produced, as to intersect the neck furrow ; midway between these two 

 lobes there is a more prominent mesial node, isolated by an accessory furrow 

 passing across in front of it, so as to cut it off, as it were, from the narrow 

 posterior central part of the glabella ; second and third lateral lobes very 

 small, transverse and obscurely defined by short, nearly obsolete linear fur- 

 rows ; anterior lobe larger than all the remaining portions of the glabella be- 

 tween it and the neck furrow. Neck segment a little higher in the middle 

 (where it is provided with a minute tubercle) than the glabella, strongly 

 arched upwards, (not forward) and more than twice as wide, antero-posteri- 

 orly, as one of the thoracic segments ; neck farrow deep, broad, and arching 

 with the neck segment. Eyes comparatively large, or half as lon<r, and (be- 

 hind) nearly as prominent as any part of the glabella, located with their po- 

 sterior margins opposite the neck furrow, and less than half their own length in 

 advance of the posterior margins of the cheeks ; visual surface ventricose, or 

 Bubhemispherical, smooth, or even polished, as seen under a good pocket lens, 

 but when examined by a high magnifying power, showing numerous, regularly 

 disposed, minute lenses, beneath the smooth, transparent, outer crust ; pal- 

 pebral lobes semicircular, convex, and resting upon the eyes like lids. Cheeks 

 as compared with the size of the eyes and glabella, small, sloping abruptly from 

 the eyes into the deep, broad, marginal furrow, which becomes suddenly ob- 

 solete on reaching the anterior lateral margins of the glabella, and extends 

 backwards to, or even a little upon the posterior lateral, subspiniferous ap- 

 pendages ; posterior margins with an elevated rim, strongly defined by the 

 deep continuation of the neck fnrrow ; lateral margins showing, as seen from 

 above, a narrow rim, which, in a side view, is seen to be deep, vertically flat- 

 tened, and marked by fine parallel longitudinal stria; ; anteriorly it continues 

 around the front of the glabella, but does not project so as to be visible from 

 above, while its upper margin is continued in the form of a carina along the 

 middle of the posterior lateral spines to their points. Fascial sutures very 

 nearly as in the last species. 



Thorax nearly as long as the head, but somewhat narrower, very distinctly 

 trilobate ; mesial lobe prominent, rounded and a little wider than the lateral 

 lobes ; its nine segments narrow, and subangular. Lateral lobes depressed 

 and flattened near the mesial lobe, and so abruptly sloping from the outer 

 side of this flattened space as to impart a slight angularity along that region ; 

 segments corresponding in size with the segments of the mesial lobe, and 



[Dec. 



