44 CARBONIFEROUS TRILOBITES. 



front of the glabella. Free-cheeks small, with a broad and very distinct margin 

 separated by a deep furrow ; the margin is striated longitudinally ; the head and 

 cheeks are scabrous, most strongly so on the posterior half of the glabella. The 

 eyes were large, nearly 3 mm. in length ; they are unfortunately wanting, being 

 represented by the cavity only. 



Thoracic segments unknown ; probably nine in number. 



Pygidium. — The coalesced series of abdominal segments forming the pygidium 

 are about fifteen in number, measuring 8^ mm. long by 10 mm. in breadth. 

 The axis of the tail is broad at the proximal end, and roundly elevated; it 

 decreases in size somewhat rapidly towards the posterior border which it overlaps. 

 The margin of the pygidium is smooth for the breadth of one millimetre. 

 Formation. — In light reddish-brown coloured shale of Carboniferous age. 

 Locality. — Vallis Vale, Frome, Somerset. 



Phillipsia scabra approaches most nearly to Ph. gemmulifera in general 

 appearance, but in the latter species the glabella is smooth, and has only two 

 oblique furrows on its sides ; the neck furrow is smooth in P. gemmulifera, but 

 finely tuberculated in P. scabra. 



The pygidium in both species shows a smooth margin, which is widest in 

 P. scabra. 



The only specimens I have seen of this species are in the Museum of Practical 

 Geology. 



22. Phillipsia carinata, Salter, MS. Plate IX, fig. 7. 



This species, named in MS. by the late Mr. Salter, is represented by two pygidia 

 in the collection of the Museum of Practical Geology, Jermyn Street. 



It owes its trivial name to the fact that the axis of the tail is acutely ridged, not 

 roundly arched as in most of the other species. At first sight this might be 

 supposed to be the result of crushing, but a closer examination shows that this is 

 not the case, both specimens being similarly ridged. 



The specimen figured (PI. IX, fig. 7) measures 12 mm. broad by 9^ mm. in 

 length, breadth of axis at the proximal border 5 mm., at the distal extremity 

 2 mm., length of axis 8| mm. There are seventeen coalesced rings in the axis, 

 and ten pleurae on each side. Most of the surface has been decorticated, but where 

 the shelly crust is preserved we see that each ring is ornamented by a single row 

 of small tubercles placed rather far apart. 



In Portlock's Geology of Londonderry and Tyrone, on pi. xi, fig. 10, there is 



