CYCLUS RADIALIS. 253 



Species 5.— CYCLUS RADIALIS :— Phillips, sp., 1836. PI. XXXII, fig. 43 a, b. 



Agnostus badialis, Phillips, 1836. Geol. Yorks., vol. ii, t. xxii, fig. 25. 

 Cyclus — H. Woodw. and Salter, 1865. Cat. and Chart Foss. Crust., 



p. 17, fig. 14. 



— — H. Woodw., 1868. Brit. Assoc. Report, p. 75, pi. ii, fig. 1. 



— — H. Woodw., 1870. Geol. Mag., vol. vii, pi. xxiii, figs. 2 and 2 a, 



p. 557. 



I was at first doubtful whether the Cyclus radialis of M. de Koninck, from Belgium, 

 really represented the Agnostus radialis (?) of Phillips, from the Carboniferous Limestone of 

 Bolland, Yorkshire. I have fortunately been able to see and examine the original speci- 

 men of Cyclus radialis of M. de Koninck (and Gilbertson's specimens from Bolland, 

 Yorkshire, preserved in the British Museum), and find that it does agree with the figure in 

 Philips's ' Geology of Yorkshire ' (vol. ii, t. xxii, fig. 25), but it entirely disagrees with 

 M. de Koninck's magnified figure. I have therefore redrawn the Belgian form (see 

 'Brit. Assoc. Rept.,' 1868, pi. ii, fig. 1). Mr. Hollick in drawing Cyclus radialis for the 

 ' Geol. Mag.,' 1870, vol. hi, was good enough to point out that the posterior border of one 

 of M. de Koninck's specimens, from the Carboniferous Limestone of Vise, Belgium, drawn 

 on our Plate XXXII, fig. 43 a, b, was not broken (as I had supposed and figured it in my 

 Report, op. cit., pi. ii), but was naturally indented upon the posterior border on each side, so 

 as to leave a rudimentary spine at the termination of the dorsal ridge, as seen in our 

 present figure. 



Cyclus radialis (fig. 43) is an elegant shield-shaped carapace, 5 lines long by 4 lines 

 in breadth ; its general form is hemispherical, with a narrow smooth border (roundly 

 indented behind, so as to leave a rudimentary medial spine in the centre) ; the shield is 

 divided down its centre by a raised longitudinal (dorsal) ridge, from which radiate seven 

 diverging ribs (transversely wrinkled), whose rounded extremities reach the lateral and 

 posterior border. 



The anterior cephalic portion occupies about a quarter of the entire shield, and is 

 ornamented by the spreading out of the raised central ridge, and by two subcentral, 

 rounded prominences, which correspond in position to eyes, but are not facetted. The 

 ribs are ornamented, each with from three to five tubercles irregularly disposed over their 

 surface. 



This species (which is the first that was published of this genus) occurs in the Carbo- 

 niferous Limestone of Little Island, Cork, Bolland and Settle in Yorkshire, and Vise, 

 Belgium. 



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