MARYLAND GEOLOGICAL SURVEY cli 



and the Oligocenc. This view was afterward corrected by von Koenen * 

 who showed that the Diestien and part of the Bolderien were a west- 

 ward extension of a fauna which he identified with that of the North 

 German Middle Miocene. 



Of eighty-nine species of this Belgian fauna Nyst regarded 19 per cent 

 as surviving, an estimate which must be materially reduced to bring it 

 into harmony with modern views. Much more reliable from this stand- 

 point is the estimate of von Koenen, who regarded out of one hundred 

 and forty-two species of gastropods 11 per cent as identical with recent 

 forms, a result practically agreeing with our estimates for the middle 

 Chesapeake of Maryland and Virginia. Of these North German species 

 43 per cent are common to the fauna of the Vienna basin, 12 per cent 

 are also known from the German Oligocene and 38 per cent from the 

 Pliocene of South Europe. The relations with the Crag of Britain are 

 less intimate, the latter being characterized by a rather colder water 

 fauna. 



In a general comparison of the European and American Miocene we 

 find, among other things which may l)e cited as parallelisms: in land 

 vertebrates the Sansans and Deep Eiver mammals, and among cetaceans 

 the presence of Squalodon, Balaena, Frisco delpMnus and other dolphins. 

 Among the sharks may be cited Carcharodon megalodon, Hemipristis 

 sen-a and Notidaniis pvlmigenius. Oxyvhina, Carchnrias, Galeocerdo and 

 various rays were abundant in the sea bordering the western continent 

 during this period. 



In Europe Corals are rare except at the south ; in Maryland Astrohelia 

 and Septastrea represent the group, the waters of Chesapeake time in 

 this region having been too cold for reef corals and too shallow for the 

 deep sea forms. 



The Echinoids of the Miocene are as a rule few in species and profuse 

 in individuals ; Chjpeaster, Scutella and Spatangus being the most promi- 

 nent of European, Amphidetus and Scutella of American forms. 



Among the Vermes Spirorbis is conspicuous, and Balanus among the 

 Crustaceans. 



••Das Miocaen Norddeutscblauds und seine Molluskfauna. Sebr. ges. Naturw. zu 

 Marburg, X, 3te Abtb., pp. 139-143, 1872. 



