

808 



PALEOZOIC TIME. 



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

 over the bed of the northern Atlantic, off Norway. Fusulina cylindrica 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) crenistria, common in the American Carboniferous; Fig. 606, Spirigera (Athyris) 

 lamellosa Dav. ; Fig. 607, Terebratula hastata Sow. : Fig. 608, Productus longispinus 

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

 tus Sow., S. disjunctus Sow.; Chonetes Dalmaniana Kon.; Orthis Mich elini 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~ 



ninckii D'Orb. 



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

 Griffithides, and Brachymetopus. Fig. 611, Phillipsia seminife.ru Morr. : 

 P. jjustulata Kon. occurs in the Irish rocks. 



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

 Cestracionts (or sharks with pavement-teeth), Cochliodus conlortus 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, Ctenacanthus major Ag. ; one specimen has a 

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

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

 nifera. have had gigantic dimensions. Another spine, Oracanthus Milleri 



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- 

 Fig. 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. 



