Zoophyta

Abstract

This class is represented by a considerable number of genera and species, some of which are so abundant in certain horizons that their stony skeletons now form whole bands of limestone. Corals, being truly marine in their habitat, are never found in the strata of our upper coal measures, nor in the brackish or fresh-water beds that alternate with the limestone series or lower coal measures. They are always associated with fossils which represent true oceanic conditions, like the marine fauna of our present seas. About twenty genera and treble that number of species have already been recorded as found in our strata; and, as the work of investigation goes on, it is likely that other forms will yet be detected. The greatest number is found in the lower limestone series, some of which seem to be characteristic of this division, such as Lithodendron, Lithostrotion, Syringopora, Cyathophyllum, Amplexus, Heterophyllia, Michelinia, etc. Several of the genera have, however, a wider vertical range, being found in the lower, as well as in the upper limestones and shales. These are chiefly Clisiophyllum, Zaphrentis, Stenopora, and Alveolites; but corals, so far as I have observed, seem to be nowhere very abundant in the upper limestone series. Many of the Scottish carboniferous corals, being embedded in soft clay shale and calcareous shale, have their internal structure better preserved than specimens obtained from hard limestone, which are often so much crystallized internally that their finer septa are in many cases entirely obliterated. The localities of easiest This 250-word extract was created in the absence of an abstract