The Liassic beds are often metamorphosed and the limestones contain garnet and wollastonite.
Accepting this view of the phylogeny of the leaf, the perianthleaves (sepals and petals) and the foliage-leaves may be regarded as modified or metamorphosed sporophylls; that is, as leaves which are adapted to functions other than the bearing of spores.
The Falkland Islands consist entirely, so far as is known, of the older Palaeozoic rocks, Lower Devonian or Upper Silurian, slightly metamorphosed and a good deal crumpled and distorted, in the low grounds clay slate and soft sandstone, and on the ridges hardened sandstone passing into the conspicuous white quartzites.
The body consists of a number of exactly similar or closely similar segments, which are never fused and metamorphosed, as in the Arthropoda, to form specialized regions of the body.
It is noteworthy that in this family only among the Polychaeta, the nephridia are not restricted to a single pair in each segment; so that the older view that the gonad ducts are metamorphosed nephridia is not at variance with the anatomical facts which have been just stated.