740 Davis — On the Fossil Fish- Remains of the Coal Measures of the British Islands. 



Borough Lee have, however, been accessible, and I have before me an example 

 from the Bone-bed above the Better-bed coal at Clifton, which corresponds exactly 

 with the Borough Lee specimens. The spine is imperfect, the distal portion 

 only being preserved; it is O'Olo in length, and there are eight or nine large 

 recurved, sharply-pointed denticles ; the surface of the spine is smooth. Except 

 that the denticles are larger, the spine agrees with the smaller examples of 

 Pleur acanthus alafus, Davis, and it is quite probable that additional specimens 

 may show a gradation of the one into the other ; for the present it is suggested 

 that the specimens should be considered as a separate species. 



Formation and Locality. — Bone-bed, Better-bed Coal, Clifton, Yorkshire. 



Ex coll. — James W. Davis. 



Pleuracanthus cylindricus (Agassiz), Davis. 

 (PL Lxxiii., figs. 1—4.) 



Orthacanthus cylindricus, . Agassiz, L., 1843, " Poiss. Foss.," vol. iii., p. 177, 



pi. XXV., figs. 7—9. 

 Orthacanthus cylindricus, . Morris, J., 1854, "Cat. Brit. Foss.," p. 335. 

 Orthacanthus cylindricus, . Baekas, T. P., 1873, "Coal Meas. Palaeont.," 



p. 20, figs. 39-42. 

 Orthacanthus cylindricus, . Ward, J., 1875, " Proc. N. StafPs. Nat. Field 



Club," p. 217. 

 Pleuracanthus cylindricus, . Davis, J. W., 1880, " Quart. Journ. Geol. Soc," 



vol. xxxvi., p. 331 (woodcut). 

 Pleuracanthus (Orthacanthus) Traquair, R. H., 1888, " Geol. Mag.," ser. iii., 



cylindricus, vol. v., p. 101. 



Pleuracanthus cylindricus, . Woodward, A. S., 1889, " Cat. Foss. Fishes Brit. 



Mus.," pt. I., p. 8. 

 Orthacanthus cylindricus, . Ward, J., .1890, " Trans. N. Staffs. Inst. Mining 



and Mech. Engin.," vol. x., p. 137. 

 Pleuracanthus cylindricus, . Woodward & Sherborn, 1890, " Cat. Brit. Foss. 



Verteb.," p. 153. 



Spine : erect and straight, or with a very slight curvature ; attains a large 

 size. A specimen in the collection of Mr. Ward, from the Fenton Ironstone shales, 

 was probably not less than 0*55 m. ; the base is imperfect, but the part preserved, 

 probably the thickest, has a diameter of 0'025 m. A more perfect specimen has a 

 length of 0'31 m., and a diameter of 0'018 m., at a distance of 0'2 m. from the apex ; 

 from this part the diameter of the spine gradually decreases upwards and ends in 



