. The ancient life-history of the earth; a comprehensive outline of the principles and leading facts of palaeontological science. Paleontology. THE UPPER SILURIAN PERIOD. 125 narrow, sword-shaped spine. Fragments of the skeleton are easily recognised by the peculiar scale-like markings with which the surface is adorned, and which look not at all unlike the scales of a fish. The most fam- ous locality for these great Crus- taceans is Lesmahagow, in Lan- arkshire, where many different species have been found. The true King-crabs {Limuli) of exist- ing seas also appear to have been represented by
. The ancient life-history of the earth; a comprehensive outline of the principles and leading facts of palaeontological science. Paleontology. THE UPPER SILURIAN PERIOD. 125 narrow, sword-shaped spine. Fragments of the skeleton are easily recognised by the peculiar scale-like markings with which the surface is adorned, and which look not at all unlike the scales of a fish. The most fam- ous locality for these great Crus- taceans is Lesmahagow, in Lan- arkshire, where many different species have been found. The true King-crabs {Limuli) of exist- ing seas also appear to have been represented by at least one form {Neolwiulus) in the Upper Silu- rian. Coming to the Molhisca, we note the occurrence of the same great groups as in the Lower Silurian. Amongst the Sea- mosses (Folyzoa), we have the ancient Lace - corals {Fefiestella and Retepora), with the nearly- allied Glauconovie, and species of Ptilodiciya (fig. 66); whilst many forms often referred here may probably have to be transferred to the Corals, just as some so- called Corals will ultimately be removed to the present group. The Brachiopods continued to flourish during the Upper Silurian period in immense num- bers and under a greatly in- creased variety of forms. The three prominent Lower Silurian genera Orthis, Stropho^nena, and Lepi(Ena are still well represented, though they have lost their former pre- eminence. Amongst the numerous types which have now come upon the scene for the first time, or which have now a special development, are Spirifera and Fentamerus. In the first of these (fig. 69, b, c), one of the valves of the shell (the dorsal) is furnished in its interior with a pair of great calca- reous spires, which served for the support of the long and fringed fleshy processes or " arms " which were attached to the sides of the mouth.* In the genus Pentamerus (fig. 70) the * In all the Lamp-shells the mouth is proTided with two long fleshy organs, which carry delicate filaments on their sides,
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Keywords: ., bookcentur, bookdecade1870, booksubjectpaleontology, bookyear1876
