PHACOPS. 29 



of Wales and Shropshire, but are rare in the Llandeilo flags. It is a smaller fossil than 

 P. Poivningia, though much like it, and is readily distinguished by the faint upper lobes 

 of the glabella, and the strongly apiculate or shortly mucronate tail. The entire fossil 

 could not have been above one and a quarter inch long, and is rather depressed than 

 convex. 



Head semicircular (smooth ?), the front bluntly angulated, or, rather, like a broad 

 Gothic arch. The glabella is long and parallel- sided, but slightly broader in front, and 

 occupies less than half the width of the head. There is scarcely any margin in front of 

 the forehead-lobe, the sides of which, above the eye, slope into the cheek without distinct 

 axal furrows at that point. These are indeed but faint throughout, but are nearly parallel 

 along the two upper lobes, and the basal lobes and neck-segment are scarcely narrower 

 than the upper lobes. The neck-segment is strong and prominent; the basal lobes are 

 transverse-oval, and deeply circumscribed, except on their inner margin. The uppermost 

 furrows straight, oblique, deepest just over the eye, and thence extended nearly to the 

 centre. The middle furrow is very faint, and gently arched upward : it nearly meets the 

 margin, but is so faint that the two upper lobes appear like one. 



The eye is small and conical, not much curved, and covers the space of the two upper 

 lobes, leaving a wide space between it and the sharp neck-furrow. There is no marginal 

 furrow to the cheeks on their outer sides, by which character it is easily distinguished 

 from the following species. There is a very short mucro to each of the head-angles. 



The tail is broad-triangular, and strikingly recalls that of P. Downingice. The largest we 

 have is seven lines wide and five long, without the short recurved apiculus. The axis rather 

 narrow, not nearly equal to the limb, regularly conic, ribbed by eight or nine distinct 

 ridges, and the smooth terminal portion is pinched up, as it were, into the short apiculus. 

 The axal furrows are not strong ; the sides are convex, declining, and with a broad concave 

 margin, not crossed by the side-furrows, which are five in number, and are deep narrow 

 grooves, interlined pretty strongly on the cast (fig. 37), but less distinctly on the outer 

 surface (fig. 38). Our figures do not express this as well as they ought to do. 



Localities. — Upper Llandeilo flag. Treiorwerth, near Llanerchymedd, Anglesea. 

 Caradoc Sandstone. Soudley, Horderly, and many other places in Shropshire ; 

 abundant ; Cerrig-y-Druidion ; Bala Lake ; Llangollen ; Meifod ; Conway River ; Pwllheli, 

 &c, in North Wales ; Coniston Water and Troutbeck, in Westmoreland. 



Phaoops (Acaste) mimus, n. sp. PI. I, fig. 35. 



P. {Acaste) minor, capite elongato (angulis obtusis?). Glabella subparallela, hand 

 convexa, lobis superioribus obscuris, basalt distincto. Oculi submediani, modici. Gena 

 lati-marginatce, sulco antico exarato. 



Though at first sight a good deal resembling P. apiculatus (p. 28), this little trilobite is 



