Page:VCH Herefordshire 1.djvu/85

 PALAEONTOLOGY genus, it may be observed, has an oval and spineless dorsal shield consisting of four pieces — two central and two lateral. The typical Cyathaspis bankst — originally described as Pteraspis — is recorded not only from the Upper Ludlow bone-bed near Ledbury, but likewise from the Downton Sandstone of Kington and elsewhere. The so-called Scaphaspis, or Pteraspis, tru?jcata, founded on Kington specimens, appears to be specifically inseparable from the former. On the other hand, a specimen from the Lower Old Red Sandstone of England's Hill Quarry, Bodenham, in the collection of the British Museum, apparently represents a second species, for which the name C. maccuUought has been suggested.^ The so-called Cyathaspis symondsi, represented by a specimen in the Museum of the Geological Survey from the Cornstones of the county, is very doubtfully distinct.' Fragments of dermal plates from the Lower Old Red Sandstone of Bush Pitch, Ledbury, perhaps referable to pteraspidians, have been named Kallostrakon podura by Professor Lankester, but nothing more definite can be stated with regard to their affinity." The Osteostraci, or second group of the Ostracodermi, which includes the families Cephalaspididae and T'remaspididae, is represented in the county by three if not four species of the typical genus Cephalaspis, easily recognized from the striking resemblance presented by its great head-shield to a cheese- cutter. Of these species, Cephalaspis lyelli and C. {Zenaspis) salweyi are common to the Lower Old Red Sandstone of certain other counties, but C. (Hemicyclaspis) murchisoni is peculiar to the Ludlow Tilestones and the Old Red passage-beds of the county. Possibly the fragments mentioned above under the name of Kallostrakon podura may really belong to this creature. Whether Cephalaspis lightbodii, apparently only known by a single specimen from the Tilestones near Ludlow, should be included in the fauna of this county or in that of Shropshire is difficult to decide. To the same family belongs Euceraspis pustulifera, a genus and species peculiar to the Upper Ludlow beds and Downton Sandstone of the county, although an allied form may occur in the Downton Sandstone of Shropshire, and another in the Palaeozoic of Dantzic. Euceraspis takes its name from the prolongation of the head-shield into a pair of long -backwardly-projecting horns. Nearly allied is Auchenaspis, in which the aforesaid horns are shorter, and there is a dorsal plate behind the head-shield, not known to be present in Euceraspsis. Of the two British species, Auchenaspis egertoni is peculiar to the Ledbury passage-beds of the Old Red Sandstone, while Au. salteri is from the Upper Tilestones of the Ludlov/ neighbourhood, and may therefore occur either in Herefordshire or Shropshire, or perhaps in both. Of the Palaeozoic armoured lung-fishes, or Arthrodira, only a single representative belonging to the typical family of Coccosteidae, or berry-bone fishes, occurs in the county ; this being Phlyctaenaspis anglica, which is a member of a genus typically from the Lower Devonian of New Brunswick. This species was described upon the evidence of specimens from the Lower Old Red Sandstone (Cornstones) of Cradley in Herefordshire, but also occurs in the corresponding formation of Heightington, Worcestershire. Next on the list comes the widely distributed fringe-finned ganoid Holoptychius, of which the large cycloid scales are said to occur in the Old Red Sandstone of Herefordshire and the adjacent counties, although they ' Cal. Foss. Fish. Brit. Mm. ii, 172. " Ibid. 172. ■» Ibid. 175. 37