488 Dr. H. Woodxcard — Carboniferous Limestone Trilohites. 



Thoracic segments unknown; probably nine in number. 



Pygidium. — The coalesced series of abdominal segments forming 

 tbe 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. 



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. 



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

 age. Localitij. — Vallis Vale, Frome, Somerset. 



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

 Museum of Practical Geology. 



Phillipsia carinata (Salter, MS.), H. Woodw. 1884. Plate XYI. 



Fig. 3. 



Phillipsia carinata, H. "Woodw. Pal. Sec. Men. Carb. Trilob. part ii. 1884, 

 p. 44, pi. 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 pygidium 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 pleuras 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 wide apart. 



In Portlock's Geology of Londonderry and Tyrone, on pi. xi. 

 fig. 10, there is a pygidium figured which seems to have been in- 

 tended for a caudal shield of this very species ; but the author makes 

 no allusion to the figure in his text, nor yet in the explanation to 

 the plate. 



This species most nearly resembles the pygidium of Ph. truncaiula, 

 Phil, sp.,^ but the acutely-ridged character of the axis in P. carinata 

 suffices to distinguish it from this and all other species. 



Formation. — Carboniferous Limestone. 



Locality. — Derbyshire. 



1 See Geol. Mag. 1883, p. 451, PL XI. Fig. 4. 



