308 



PALEOZOIC TIME. 



of the genus thus far described is the Sacctmmina sphcerica Sars, a species now living- 

 over the bed of the northern Atlantic, off Norway. Fusulina cylindrical Vern. occurs 

 in Russia, Spain, etc.; F. robusta M., in Russia, Southern Alps, Armenia: neither species 

 has been found in Great Britain. 



Among Mollusks: Fig. 605, Hemipronites (formerly Streptorhynchus or Orthis umbrac- 

 ulum) c rent dria, common in the American Carboniferous; Fig. 606, Spirir/era (Athyris) 

 lameUosa Dav. ; Fig. 607, Terebratula hastata Sow.: Fig. 608, Product us' longispinus 

 Sow., P. scabriculus Sow.; Fig. 609, Spirifer glaber Sow., S. speciosus Br , S. cuspida- 

 tus Sow., S. disjunct us Sow.; Chonetes Dalmaniana Kon. ; Orthis Mickelini Morr., O. 

 resupinata Phill. Pleurotomaria carinata Sow. retains its original colored markings, 

 as first observed by the late Professor Forbes; this author hence inferred that it was a 

 shallow-water species, but it is now known that colored species occur 

 Fig. 611. at a great depth in the ocean. Fig. 610, Nautilus (Trematodiscus) Ko~ 



ninck'd D'Orb. 



Trilobites occur, of the only three Carboniferous genera, Phillipsia, 

 Grijfithides, and Brachymetopus. Fig. 611, Phillipsia seminifera Morr.: 

 P. pustulata Kon. occurs in the Irish rocks. 



Remains of fishes are very common in Europe and Britain. Among 



Cestracionts (or sharks with pavement-teeth), Cochliodus contortus Ag., 



Fig. 600 A; among Hybodonts (or sharks with regular teeth, the teeth 



with obtuse or rounded edges), Cladodus marginatus Ag. Fig. 612, 



part of the fin-spine, Ctenacnnthus major Ag. ; one specimen has a 



length of fourteen and a half inches, and was probably eighteen inches 



Phillipsia semi- m the living Cestracicnt. The old fishes, as Agassiz observes, must 



nifera. have had gigantic dimensions. Another spine, Oracanthus Millei-i 



Ag., is nine and a half inches long and three inches wide at base; 



and yet it has lost some inches at its extremities. These species and many other re- 



Fiff. 612. 



Part of a spine of Ctenacanthus major. 



mains of fishes are found in fish-bone beds in the limestone at Bristol, England, and at 

 Armagh, Ireland. 



3 Disturbances Preceding the Carboniferous Period. 

 It has been stated, on page 290, that the Coal-measures, in parts of 

 northern and western Illinois, rest on tilted Silurian strata ; and the 



fact is illustrated by a section from La 

 Salle County. Another section, pub- 

 lished by Hall, is shown in the annexed 

 figure ; it represents the Coal-measures 

 (A), in Rock Island County, at Port 

 Byron, overlying upturned Niagara beds (B). Like that of La Salle 



Fig. 612 A. 



