﻿Vol. 66.1 DERBYSHIRE AND NOTTINGHAMSHIRE COALFIELD. 339 



seriously challenging Seward's specific name. This specimen is of 

 especial interest, in that it shows that the cast of the fossil (op. cit. 

 fig. 2) is Spiraxis ; while the impression in the matrix is a typical 

 Fayolia. 



The materials from Shipley available for description are: — (1) Two 

 fragments of a large uncompressed Fayolia, which are so alike, and 

 were found so close together on the floor of the claypit, that there is 

 great probability that they form parts of the same individual ; with 

 parts of their encasing nodules, which give an exact copy of the 

 central fossil : (2) one fragment of a somewhat larger example, with 

 its counterpart : (3) a nodule containing crushed and broken frag- 

 ments of another example : and (4) the above-mentioned compressed 

 specimen of a smaller Fayolia, evidently of a different species. 



Fayolia crenulata, sp. nov. 1 (PI. XXVI, figs. 2-3 & PI. XXVII, 

 fig. 1.) 



The largest fragment (PI. XXVI, fig. 3) consists of a flattened 

 cylinder tapering gradually towards the base, the cross-section of 

 which is more or less a perfect oval, 5*6 cm. wide at its upper part, 

 4*5 cm. wide at its base, and 11 cm. long, broken off transversely at 

 each end and consequently showing no termination ; composed of 

 two finely striated valves 2*1 cm. broad, fused together along their 

 edges, forming a spiral with two and a half turns. The line of 

 fusion of the valves is marked by a coarse line, and 3 mm. above 

 this occurs another coarse line ; again, 8 mm. above the fused 

 border occurs a row of circular scars 2 mm. in diameter and placed 

 4*6 mm. apart, so that ten scars can be counted in 38 mm. Just 

 above the row of scars is seen a crenulate line of ornamentation with 

 & marked double contour, each dip in the crenulation corresponding 

 to a scar. This ornamentation will be discussed later, in relation to 

 the ' collerette.' The whole area, from the line of fusion of the valves 

 to the top of the crenulate margin, projects markedly from the plane 

 of the cylinder. The striations on the valves, running exactly 

 parallel to the turns of the spiral, are for the most part fine lines ; 

 but there are to be noticed coarser striations irregularly disposed 

 (PI. XXVII, fig. 1), two of which, however, usually run close together 

 near the centre of the valve. The scars are not facets, but show 

 ■an irregular broken surface, as if spines had been attached to 

 them and had been broken off. 



There is evidence of a distinct, membranous, finely striated 



* collerette,' 12*75 to 15 mm. wide, arising from the line of 

 junction of the valves, and making an angle of about 30° with the 

 face of the fossil : its free crenulate margin gradually bending 

 outwards to about a right angle. This ' collerette ' can be clearly 

 seen on some of the fragments of the encasing nodule, and also on 

 the matrix in some places adhering to the fossil (PI. XXVI, fig. 3, 

 and PI. XXVII, fig. 1, A). It seem3 impossible to explain 

 the crenulate ornamentation just above the line of scars, without 

 coming to the conclusion that there was another, probably more 



• l This specimen was informally brought before the Geological Society by 

 Mr. E. T. Newton, F.R.S., in the autumn of 1904. 



