IN THE MANCHESTER MUSEUM. 25 



considerably narrower as these approach the centre, 

 near the posterior region of the carapace. The median 

 ridge ends in front, close to the outer pair of oval pro- 

 minences ; two other rather semicircular smooth raised ridges, 

 broader and shorter than the preceding ridge (by which, 

 indeed, they are encircled), occupy the inner and more 

 central portion of the shield, the outer one commencing 

 near to the inner one on the central ridge, at 5mm. distance 

 from the posterior border, and curving forwards until they 

 touch the posterior ends of the two pairs of oval prominences 

 near the front of the carapace. In the centre, between these 

 raised ridges and the oval bodies, is a small lozenge-shaped 

 area, which is continued backwards till it unites with the 

 median ridge of the shield. The surface of the shield 

 (particularly the posterior portion) is very finely granulated 

 with minute circular and oval pustules (see wood-cut, Fig. B). 

 No eye-spots are observable (unless a pair of the oval pro- 

 minences in front may represent eyes). There is no trace 

 of any appendages to be discerned on the matrix. 



Observations. — Of the seven species of Cyclus described 

 by me from this country, six are from the Carboniferous 

 Limestone of Yorkshire and Ireland (see Geol. Mag., 1870, 

 vol. vii., pp. 554-558, pi. 23), and one from the Coal- 

 Shales of Carluke, Scotland (see Brit. Assoc. Reports, 1868, 

 p. 72, pi. ii., fig. I, and op. cit.) Several specimens, not 

 yet described, were obtained, many years since, from the 

 Pennystone Ironstone, over the thick coal of the Staffordshire 

 Coal-field, at Coseley, near Dudley, by the late Mr. Henry 

 Johnson, C.E., F.G.S., of Dudley, and an account of them 

 will be shortly published. 



In general outline this species from Bacup resembles 

 most nearly Cyclus (Halicyne?) agnotus, H. von Meyer, sp., 

 from the Muschelkalk of Rottweil, Germany (see Palaeonto- 

 graphica, 1847, i., p. 234, pi. xix., fig. 23), but it differs 

 in having an indentation or notch in the posterior border, 

 whereas the German specimen has a small prominence. The 



