UPPER SILURIAN. 245 



In Scandinavia, the limestones and sandstones of Gothland represent the Niagara, 

 and the Calciferous flags and Upper Malmo group the Lower Helderberg. In Bohemia, 

 the rocks iuclude the limestones and schists of Barrande's formations E, F, G, H. 



Life. — 1. Plants. — Besides sea-weeds, there are the remains of ter- 

 restrial plants. In the Upper Ludlow beds, occur seed-vessels called 

 Pachytheca by Hooker, and also fragments of stems, supposed to be 

 those of Lycopods (Ground Pines) related to the Psilophyton. In 

 Germany at Lobenstein, and at Hostin in Bohemia, Lycopods of the 

 Lepidodendron family occur — a kind having the bark marked regu- 

 arly with scars where the leaves have dropped off, similar to those on 

 i young dry branch of a spruce. The word Lepidodendron is from 

 A.€7rt5, sccde, and Sei 8p»v, tree, the bark, owing to the scars over it, often 

 looking as if scale-covered. The species are referred to the genus 

 Sagenaria. These plants, like modern Lycopods, had much of the 

 habit of the spruce or pine tribe. For figures see pages 323, 324. 



Besides these flowerless species (Cryptogams), others of genera of 

 the Pine tribe — the lowest division of flowering plants (Phenogams) 

 — are supposed by Dawson to have existed, he referring pieces of 

 carbonized wood in the Upper Ludlow beds to the genus Prototaxites 

 (so named from 7rpojT09, first, and taxus, yew -tree). Carruthers con- 

 siders the plant a sea-weed. 



2. Animals. — The range of Invertebrate animal life and the 

 general types are similar to those of America, while the species are 

 for the most part different. 



A few species are represented in Figs. 477 to 482. Figs 477, 477 a represent a 

 Cyathophylloid coral Omphyma turbinatum'M. Edw., of the Wenlock, reduced one-half 5 

 478, a section of another coral, a species of Cystiphyllum, from the same beds ; 479, a 

 peculiar Crinoid, Crotalocrinus rugosus Miller, from the Wenlock ; 480, the Pentamerus 

 Knightii Sow., a characteristic fossil of the Aymestry limestone; 481, a Lamellibraneh, 

 Grammysia cingulata Morris, of the Dudley limestone: 482, the Crustacean, Ptery- 

 yotus bilobus Salter, from the upper Ludlow; and 482 a, one of the jaws. The ear- 

 liest species of these Pteryyoti occur in the upper beds of the Upper Llandovery, the 

 lower part of the Upper Silurian ; while in North America none have been "found 

 below the Lower Helderberg. 



Besides Invertebrates, there were the earliest Vertebrates — Fishes. 

 The first (Pteraspis) is from the lower Ludlow. Fig. 483 a repre- 

 sents Pteraspis Banksii Huxl. & S., a head-shield, related to the fol- 

 lowing. Fig. 483 b is the head-shield of a Cephalaspis — so named 

 from the Greek for a shield-like head ; a complete animal, but different 

 in species, is shown on page 286. Fig. 483 d, represents probably 

 part of the jaw-bone of a Cephalaspis. 



Other fishes were of the shark tribe. Fig. 483 c, represents a spine 

 from the margin of the fin of one of them ; and 483 e, two of the 

 minute pieces much magnified (the natural size is shown in the upper 



