11 b* PAL.-EONTOLOGY. 



Cephalopoda. — Aturia, Discites, Nautfloceras, Trigonoceras, 

 Teinnochilus, Lituites, Trocholites, Trochoceras, Cly- 

 menia ; Orthoceras, Camaroceras, Huronia, Actihoceras, 

 Discosorus, Gonioceras, Tretoceras, Apioceras, Gompho- 

 ceras, Phraginoceras, Cyrtoceras, Gyroceras, Ascoceras ; 

 Goniatites, Bactrites, Ceratites, Ammonites, Crioceras, 

 Toxiceras, Ancyloceras, Scaphites, Helicoceras, Tur- 

 rilites, Hamites, Ptychoceras, Baculites ; Mastigophora, 

 Teuthopsis, Celaeno, Beloteuthis, Geoteuthis, Belopeltis, 

 Plesioteutliis, Leptoteuthis, Belemnites, Acanthoteuthis, 

 Helicerus, Conoteuthis, Coccoteuthis, Belosepia, Spiruli- 

 rostra, Beloptera, Belemnosis. 



Province IV.— YEETEBEATA. 



There is an enormous series of subaqueous sediment, 

 originally composed of mud, sand, or pebbles, the successive 

 bottoms of a former sea, derived from pre-existing rocks, 

 which has not undergone an}' change from heat, and in which 

 no trace of organic life has yet been detected. These non- 

 fossiliferous, non-crystalline, sedimentary beds form, in all 

 countries where they have yet been examined, the base-rocks 

 on which the Cambrian or oldest Silurian strata rest 



Whether they be significative of ocean abysses never 

 reached by the remains of coeval living beings, or whether 

 they truly indicate the period antecedent to the beginning of 

 life on this planet, are questions of the deepest significance, 

 and demanding much farther observation before they can be 

 authoritatively answered. 



It has been shewn that every type of invertebrate animal 

 is represented in the superimposed stratified deposits called 

 Cambrian and lower Silurian. In rocks of the latter age 

 in Kussia have been found minute, glistening, slender, conical 

 bodies called " Conodonts," hollow at the base, pointed at the 



