130 Guide to the Invertehrata. 



GALLEEY Cabrieres, in Languedoc, and in Saxony. In jaspers of Devonian 

 ^- age in Siberia, and in the Kieselschiefer of Hesse and Nassau, 

 Wall-case ^-^^^ ^^^ abundant. Widely-distributed beds of chert and siliceous 

 case 16. shale, filled with their remains, have been found in the Lower 

 Culm or Carboniferous strata of Devonshire and Cornwall, and 

 in jasper and whetstones of the same age, in the Harz, the Ural 

 Mountains, and in Sicily. Eadiolarian rocks of Triassic age have 

 been met with in Hungary; of Liassic age in Hanover and the 

 Tyrol; and of Jurassic age in Italy and Hungary. Beds of 

 considerable thickness of radiolarian chert, and probably of 

 Cretaceous age, form part of the coast ranges of Southern Cali- 

 fornia, and these same organisms occur in Cretaceous beds in 

 Westphalia, Manitoba, and occasionally in the Upper Chalk of 

 this country. 



The Iladiolaria in the Mesozoic and Palaeozoic rocks usually 

 occur in hard massive beds of chert, hornstone, jasper, or in hard 

 siliceous shales or kieselschiefer, which appear to have been 

 mainly formed of their siliceous skeletons. In these rocks the 

 organisms can only be studied by making thin microscopic sections. 

 In most cases the Iladiolaria in these rocks have had their latticed 

 walls dissolved away, and only the casts of their shells, which 

 appear as circular, oval spots of transparent silica, have been 

 pieserved. Exceptionally, pieces of the rock are met with in 

 which the structures are retained, and they are found to possess 

 equally as delicate and beautiful tests as the living forms of the 

 group. 



Iladiolaria have been divided by Haeckel into the four suborders 

 of Acantharia, Spumellaria, Nassellaria, and Phoeodaria, but only 

 the second and third of these are found fossil. In the Spumellaria 

 the tests are principally spherical, ellipsoidal, or discoidal in shape 

 (Fig. 180, 1, 2, 4)» whilst in the Nassellaria they are usually 

 conical or bell-shaped (Fig. 180, 3). 



GALLERY 2. — Foraminifeea. These also belong to the most lowly 

 organisms of the animal kingdom. Their soft structures consist 

 case 16 ^^ sarcode, an albuminous substance of a jelly-like con- 

 Wall- sistency and contractile character, which has the power of 

 sending out thread- or finger-like processes called pseudopodia, 

 which coalesce with each other, and can readily be emitted 

 from, and again withdrawn into, the body - substance. The 



