54:2 DEVONIAN BRACHIOPODA. [Ch. XXVI. 



acteristic Rhenish fossils are met with. The broad-winged Spirifers 

 which distinguish the " Spirifer-sandstein " of Germany have their 

 representatives in the Devonian strata of North America (see fig. 615). 



Among the Trilobites of this era several large species of Homa- 

 lonotus (fig. 616) are conspiucous. The genus is still better known as 

 a Silurian form, but the spinose species appear to belong exclusively to 

 the " Lower Devonian," and are found in Britain, Europe, and the 

 Cape of Good Hope. 



With the above are associated many species of Brachiopods, such 

 as Orthis, Leptama, and Chonetes, and numerous Lamellibranchiata, 

 such as Pterinea ; also the very remarkable fossil coral called Pleuro- 

 dictyum problematicum (fig. 617). 



Devonian of Russia. — The Devonian strata of Russia extend, accord- 

 ing to Sir R. Murchison, over a region more spacious than the British 

 Isles ; and it is remarkable that, where they consist of sandstone like 

 the " Old Red" of Scotland and Central England, they are tenanted 

 by fossil fishes often of the same species and still oftener of the same 

 genera as the British, whereas when they consist of limestone they 

 contain shells similar to those of Devonshire ; thus confirming, as Sir 

 Roderick observes, the contemporaneous origin previously assigned to 

 formations exhibiting two very distinct mineral types in different parts 

 of Britain.* The calcareous and the arenaceous rocks of Russia above 

 alluded to alternate in such a manner as to leave no doubt of their 

 having been deposited at the same period. Among the fish common 

 to the Russian and the British strata are Asterolepis Asmusii before 

 mentioned ; a smaller species, A. Minor, Ag. ; Holoptychius nobilissimus 

 (p. 525); Dendrodus strigatus, Owen; Pterichthys major, Ag. ; and 

 many others. But some of the most marked of the Scottish genera, 

 such as Cephalaspis, Coccosteus, Diplacanthus, Cheir acanthus, &c, 

 have not yet been found in Russia, owing perhaps to the present im- 

 perfect state of our researches, or possibly to geographical causes 

 limiting the range of the extinct species. On the whole, no less than 

 forty species of placoid and ganoid fish have been already collected in 

 Russia, some of the placoids being of enormous size, as before stated, 

 p. 533. 



Devonian Brachiopoda. 



The preponderance of the Brachiopods or Palliobranchiata among 

 the bivalve shells forms a decided feature in the conchology of the 

 Devonian strata as contrasted with that of rocks newer in the series, 

 such as have been described in the preceding chapters. In a table of 

 British fossils, constructed by Professor Ramsay, it appears that there 

 are twice as many species of Brachiopods as of Lamellibranchiate 

 bivalves in the Devonian rocks, there being ninety-six known Brachio- 



* Siluria, p. 329. 



