Page:The South Staffordshire Coalfield - Joseph Beete Jukes - 1859.djvu/132

114 the hands of Messrs. Fletcher and Gray, and are yet unpublished. The Cystidæ belong to another order of Echinoderms, and of these there are no less than ten species of the genera Apiocystites, Echino-encrinites, Ischadites (a doubtful Cystidean), Prunocystites, and Pseudoerinites; all which are described by Prot. Forbes in the Memoirs of the Geological Survey. Of true Crinoids we have no less than 23 forms already catalogued, but double that number are yet undescribed. Among the more conspicuous are the Crotalocrinus rugosus, a crinoid with net-like arms and a singular tuberculate stem, covered at its lower part with root-like processes.

Cyathocrinus, four species.

Dimerocrinus decadactylus and D. icosidactylus. The names imply the difference of character in the arms.

Of the genus Eucalyptocrinus, with its massive stomachal plates, two species occur at Dudley. E. decorus and E. polydactylus, and one at Walsall, E. granulatus. ''Platycrinus? retiarus'' is not rare.

Cheirocrinus serialis is a remarkable pendulous form. Marsupiocrinus celatus, two species of Pisocrinus (a minute fossil), Tarocrinus tuberculatus, and Icthyocrinus pyriformis, with Glyptocrinus expansus, are quite common fossils; and the long necklace-like stems of Pertechocrinus moniliformis occur on almost every slab of Dudley limestone.

The corals are still more numerous, and though there is no evidence that the Dudley limestone possessed the character of a coral reef, yet the floor of the sea must have been nearly covered with them. They are chiefly solitary forms, however, never exceeding a foot or two in diameter, and even this is rare. The more massive compound ones are Acerrularia ananas, Arachnophyllum typus, Cyathophyllum truncatum, Favosites alveolaris, and F. Gothlandica; the chain coral, and Heliolites interstinctus; occasionally one or other of the five species of Syringopora, Sarcinula organum. Linn., is more commonly Lower Silurian. Of the large cup corals, Cystiphyllum Siluriense and C. cylindricum, Cyathophyllum angustum, Ptychophyllum patellatum, and Zaphrentis lata, are conspicuous, with Omphyma turbinatum, the largest and commonest of all. Three species of Paleocyclus, a little mushroom coral, are beautiful forms. The smaller Millepores and branched corals are the most numerous. Alveolites Labechei, A. repens and A. seriatoporoides, Chatetes Fletcheri, Conites intertextus, C. juniperinus, and C. labrosus are minute-celled species. Favosites cristata has larger tubes. Two or three species of Heliolites, such as H. Grayi, H. petalliformis, and H. tubulatus, Labechia conferta, Thecia Swindernana. The last four species are everywhere found in Wenlock limestone.

There are a good many minute coral-like forms now more correctly referred to the Bryozoa, some of which are encrusting and parasitic (Diastopora and Discopora), others have free cup-like or net-like fronds, Fenestella, Polypora, Glauconome. Some are foliaceous, like the Eschara of our coasts; Ptilodictya lanceolata and P. scalpellum represent these, and are very common species.

Many of the brachiopod shells have been quoted above from the lower limestone band. To these the following must be added, and the more abundant ones are indicated by asterisks:—