OF DENISON UNIVERSITY. 9 



Clinton fauna of Ohio, however, is not at all like that of the Caielph 

 in character, but it possesses some feautures in coaimon with that of 

 the Waldron beds, and a small number of identical species.* This 

 would indicate a lower horizon for the Waldron l>eds than for the 

 Guelph beds, and a still lower one for the Clinton beds of Ohio. The 

 fact that the Clinton Group of Ohio contains a number of fossils sig- 

 nifying a low horizon, such as Rliinopora verrucosa, Pliylloporina angu- 

 lata, Leptivna prolongata, Stmphomena paienta, Mtrstella umhonata^ 

 Belieroplwn fisccUo-striatus, and Discosorus conoiJeus, and the fact 

 that the Waldron beds have no such types, is additional evidence in fa- 

 vor of the lower horizon of the Clinton Group of Ohio. That the 

 Clinton Group of Ohio should begin to assume the ficies of the Wal- 

 dron beds of Indiana, and the Waldron beds of Indiana, that of the 

 Guelph series above, are facts which ihe paleontologist will recognize 

 as being of frecpae.n occurrence, and indicating consecutive develop- 

 ment of life. Moreover, it is not necessary to imagine that the vari- 

 ous strata mentioned must either be exact equivalents or entirely dis- 

 tinct from one another. While life ceased at one locality it was still 

 continuous for some time at another, more or less removed, and new 

 types gradually introduced in those localities where life has been con- 

 secutive, seem to have been introduced suddenly into the locality 

 where life for a while had ceased, whereas it is only a case of the re- 

 introduction of a faunna in one place after life had ceased for some 

 time, from some other locality where life had been continuous, and 

 where the change of the fauna had been gradual. Geological divis- 

 ions are af'er all only convenient methods of reference, and divisions 

 are regul ited largely according to the numl)er of breaks in the fauna! 

 development of any region. Every experienced paleontologist, how- 

 ever, kn<jws that wh it are breaks in the development of life at one 

 place are gradually bridged over at some other locality. '1 his feature 

 is in small part shown by the Clinton and Waldron beds of the West. 

 Indeed, the Clinton of Ohio is itself a connecting bridge between the 

 Clinton and Niagira. as shown in New York, and Dr. E. N. S. Ringne- 

 berg has found another connecting bridge at I,ocki)')rt, N. Y., be- 

 tween the divisions themselves. .\g lin, the .Vnticosli (]roup of Cana- 

 dian geologists is a connecting bridge bet^veen the I'pper an I I-ower 

 Silurian series of rocks. This illustrates the fict, well known among 

 students of ancient life, th U geological divisi»)ns are not universally 



