BRITISH FOSSILS. 



7 



l©be is very large, and the lateral ones minute and pressed against tlie sides, as in that 

 species, but the former is parallel-sided instead of oval, not nearly so convex, and instead 

 of being covered equally with small tubercles, is studded with a double row, five on each 

 side and a terminal one, of large boss-like ones, between which the surface is finely 

 granulated. Similar large tubercles occur on the space between the glabella and the 

 forward eyes, and even on the front margin. If it were more complete (we have only 

 the central part of the head without the cheeks), it might be called A. biserialis. 



5. There is a narrow transverse caudal shield, also from the Chair of Kildare, the hinder 

 margin of which is closely serrated by 19 long spines, the primaries being not much longer 

 than the others. It resembles A, radiata^ Goldfuss. 



Lastly in the Llandeilo or Bala rocks (" Caradoc sandstone ") of Shropshire, a small 

 and pretty species, half an inch long, occurs. It has six terminal spines to the tail, as in 

 A. Jamesii, but the primaries are more divergent, as are the spines of the thorax. The 

 head has longer spines at the angles, and the glabella is truly triangular and very distinct 

 from the cheeks, the lowest lobes much larger than the second, and the uppermost quite 

 obscure. The eyes are more backward and the cheeks much smaller. We may define it 

 thus : — 



6. A. Caractaciy sp. nov. A. semiuncialis, capite semilunari convexo, glabella late 

 triangulatd, tuberculatd, a genis convexis bene distincta, utrinque bilobatd ; lobo basali cen- 

 tralem cequante rotundo circumscripto, quam secundo duplo latiore, hoc distinctissimo obovato : 

 superiori obsoleto : [cervice — ?] thorace axi convexo, pleuris ad apices dejiexis bispinosis^ 

 Cauda 12 (yeZl4?) dentata, spinis primariis fortibus paullum divaricatis^ terminalibus 

 minuiis 6, externis 2 (vel 3) ; axi convexo. 



Locality. — Gretton quarry, near Cardington ; a locality rich in all the characteristic 

 Bala species. Lichas laxatus, Phacops conophthalmus, and P. truncato-caudatus, 

 Calymene JBlumenbachii, Illcenus, &c. occur with it. 

 The species which is to be considered the true type in Britain of the section Acidaspis 

 proper, is the A. Brightii, Murchison, which we hope, with the assistance of our friends 

 at Dudley, to publish hereafter. Several British species will then be enumerated as 

 belonging to that section, and among them a new species, A. coronatus, Salter, formerly 

 called^. Brightii (Mem. Geol. Surv., 1. c. pi. 9. f. 8. 9.) 



J. W. Salter. 



August, 1853. 



