PHACOPS. 33 



Axis rather large, not equal to the limb, conical, rounded at the tip, and reaching less than 

 four fifths of the whole length ; anrmlated throughout by about nine rings ; the sides with 

 seven furrows directed obliquely, and reaching nearly to the margin, interlined throughout. 



The species is unlike any other, but has perhaps its nearest relations with P. alifrom, 

 next described. From that species the shape of the forehead-lobe will distinguish it, 

 while there is only some general resemblance ill the shape of the flatter glabella, and 

 especially in the small, greatly curved eye. 



Locality. Caradoc Rocks flf Waterford ; Tyrone. (Mus. Pra'ct. Geology.) 



PfiAcors (Acaste) alifrons, Salter. PI. I, fig. 31 — 34. 



Piiacops alifkoxs, Sailer, in Appendix to Sedgwick's Synops. Woodw. Foss., fasc. ii, 



tab. 1 g, figs. 12—14, 1852. 

 — — Ibid. In Decade 7, Geol. Survey, Art. l,p. 10, 1853 ; and Morris's 



Catal., 2nd ed., 1854. 



P. {Acaste) capite tuberculato sesquiunciam lafo, gibboso, antice truncato, bis quam 

 longo laliori. Glabella elevafa sed paullum convexa, ad basin angustata, superne dilafafa 

 obtitsa truncata, lateribus subrectis ; lobo frontali brevi transversa KmbUm crassum 

 impendenle, utrdque angulis tumidis cum margine genarum confluentibus ; lobis lateralibus 

 tumidis, supremo subtrigono modico, reliquis fere rotundas abbreviatis ; gen is declivibus 

 marginatis. Oculi curvati. Cauda semicircularis tumida, axi lafo convexo 8 — 9 annulato, 

 apice obtuso nee marginem attingente ; lateribus convexis, costis 7 — S simplicibus ; margine 

 a i) gusto. 



We are compelled to be minute in the specific characters of these species of Phacops, 

 as they really differ but in proportional characters; yet, if it were allowable to abbreviate, 

 it would certainly be excusable in this case, for in no other species which I know does the 

 outer and upper angle of the glabella run out distinctly into the margin as it does in this 

 fossil. But three or four heads of it are yet known, and two or three caudal shields 

 associated (not in actual contact). 



The species was a tolerably large one, the head (in our largest specimens, copied from 

 the figure formerly given by myself in Professor Sedgwick's work) is \\ inch broad. 

 The entire form may have been 3 inches long. The lesser figure (fig. 33) represents a 

 somewhat smaller, but characteristic specimen. Both are from North Wales, and I do 

 not know it elsewhere. 



The head is highly convex, and rather strongly truncated in front, but the glabella, 

 though tumid, is rather depressed on its upper surface. It is very wide in front, the 

 upper lobe overhanging the eye ; and being connate with the thickened border of the 

 cheek, seems to be drawn out into it. The lateral lobes are short, the upper largest, but 

 not greatly so, triangular ; the upper furrow which bounds it running nearly straight 

 across (not upward, as in P. Jamesii) ; the second, as deep, directed downward and out- 



